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Home / DTC / P1212 — Mass Air Flow Circuit Intermittent Low

P1212 — Mass Air Flow Circuit Intermittent Low

Detailed page for trouble code P1212.

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P1212

BUICK P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: BUICK
Type: P — Powertrain
Views: UK: 18 EN: 49 RU: 21
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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P1212

CADILLAC P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: CADILLAC
Type: P — Powertrain
Views: UK: 23 EN: 45 RU: 20
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
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Code

P1212

CHEVROLET P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: CHEVROLET
Type: P — Powertrain
Views: UK: 23 EN: 47 RU: 24
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
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Code

P1212

CHRYSLER P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: CHRYSLER
Type: P — Powertrain
Views: UK: 23 EN: 42 RU: 22
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
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Code

P1212

FORD P — Powertrain

Injector Control Pressure Not Detected During Crank

Brand: FORD
Type: P — Powertrain
Views: UK: 19 EN: 42 RU: 20
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1212

GM P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: GM
Type: P — Powertrain
Views: UK: 17 EN: 41 RU: 19
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1212

GMC P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: GMC
Type: P — Powertrain
Views: UK: 18 EN: 44 RU: 24
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

HUMMER P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: HUMMER
Type: P — Powertrain
Views: UK: 7 EN: 20 RU: 6
AI status
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Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

LAND ROVER P — Powertrain

Injector control pressure below desired (engine crankshaft or) operation

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 6 EN: 17 RU: 6
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

LINCOLN P — Powertrain

Injector Control Pressure Not Detected During Crank

Brand: LINCOLN
Type: P — Powertrain
Views: UK: 23 EN: 41 RU: 22
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

MERCURY P — Powertrain

Injector Control Pressure Not Detected During Crank

Brand: MERCURY
Type: P — Powertrain
Views: UK: 19 EN: 42 RU: 20
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

MINI P — Powertrain

Exhaust gas recirculation (EGR) valve actuator - circuit high

Brand: MINI
Type: P — Powertrain
Views: UK: 2 EN: 3 RU: 1
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

NISSAN P — Powertrain

ABS TCS Communication Line

Brand: NISSAN
Type: P — Powertrain
Views: UK: 21 EN: 43 RU: 24
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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P0101 P0102 P0103 P0112 P0107
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Code

P1212

OLDSMOBILE P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: OLDSMOBILE
Type: P — Powertrain
Views: UK: 20 EN: 41 RU: 20
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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Code

P1212

Other P — Powertrain

Injector Control Pressure Not Detected During Crank

Brand: Other
Type: P — Powertrain
Views: UK: 25 EN: 67 RU: 23
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1212

SAAB P — Powertrain

IAC, Output From Control Module High

Brand: SAAB
Type: P — Powertrain
Views: UK: 0 EN: 2 RU: 1
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1212

SATURN P — Powertrain

Mass Air Flow Circuit Intermittent Low

Brand: SATURN
Type: P — Powertrain
Views: UK: 20 EN: 46 RU: 23
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Loose, corroded, or damaged MAF sensor connector or pins
  • Broken or chafed wiring between MAF and PCM (intermittent open/short to ground)
  • Contaminated or failing MAF sensor element (dirt, oil, silicone)
  • Poor ground or reference voltage to the MAF
  • Intake air leaks downstream of the MAF (unmetered air)
  • Intermittent PCM input or internal PCM fault

Symptoms

  • Check Engine Light (CEL) illuminated, fault stored
  • Intermittent rough idle, hesitation or stumble on acceleration
  • Reduced engine power or limp-home behavior
  • Surging or stalling at idle or low speed
  • Higher than normal fuel consumption or black smoke (running rich)
  • Difficulty starting (occasional)

What to check

  • Read and record freeze frame and live MAF PID data with a scan tool; note conditions when fault sets
  • Visual inspection of MAF connector, pins and wiring for looseness, corrosion or damage
  • Wiggle-test wiring and harness while monitoring MAF signal for intermittent changes
  • Inspect air filter, intake snorkel and clamps for contamination, oil, or leaks
  • Check power (usually switched 12 V or fused supply), 5 V reference (if applicable) and ground at the MAF
  • Backprobe MAF signal while revving engine to confirm signal increases smoothly with throttle

Signal parameters

  • MAF signal should be stable and increase with engine load; should not drop to 0 V while engine running
  • Typical reference/supply: 5 V reference (varies by vehicle) and good chassis/engine ground
  • Typical MAF signal voltage range: ~0.5–4.5 V (varies by sensor/engine). At idle the signal is usually low-mid range and rises with RPM
  • Hot-wire MAF reports mass airflow in g/s; values vary by engine displacement and rpm (compare to manufacturer live data)
  • If vehicle uses frequency output, frequency should increase smoothly with RPM rather than drop intermittently

Diagnostic algorithm

  1. Retrieve DTC, freeze frame and live data. Note engine rpm, load, temp and MAF value when fault occurs.
  2. Clear the code, perform a road/drive cycle and try to reproduce. Monitor MAF live PID for intermittent low readings.
  3. Visually inspect MAF connector and wiring. Repair any damaged insulation, pins or corroded terminals.
  4. With key on (engine off), verify 5 V reference (if present) and power supply to the MAF; verify ground continuity to chassis/engine and to PCM.
  5. Backprobe the MAF signal with a digital multimeter or scope while starting and revving the engine. Look for drops to near 0 V, noise, or erratic behaviour.
  6. Wiggle harness and connectors while monitoring signal to reproduce intermittent fault. Repair wiring or secure connectors if fault correlates.
  7. Inspect and, if contaminated (oil, dirt, silicone), clean the MAF only with approved MAF cleaner per service manual. Do not use carb cleaner or degreasers on hot-wire elements.
  8. Check for intake leaks downstream of the MAF (vacuum smoke test or pressure test). Repair leaks and retest.
  9. If wiring, power and ground check good but signal still intermittent, swap with a known-good MAF (or bench test MAF per spec) to confirm sensor failure.
  10. If new sensor also fails or intermittent persists, inspect PCM connector and perform continuity to PCM pin; consider PCM diagnosis or reflash if wiring and sensor are good.
  11. After repair, clear codes and perform drive cycle to verify the fault does not return.

Likely causes

  • Loose/poor connector or wiring fault at the MAF (most common)
  • Contaminated or failing MAF element
  • Intermittent ground or 5V reference supply issue
  • Intake leak causing inconsistent measured airflow
  • Less likely: PCM fault

Fault status

⚠️ Status
Mass Air Flow Circuit Intermittent Low — intermittent low/erratic MAF signal detected; inspect sensor, wiring, power/ground and intake for faults.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

P0101 P0102 P0103 P0112 P0107
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

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