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Home / DTC / P0102 — The Mass Airflow Sensor (MAF) Sensor is unplugged or the wiring is damaged, Loose or corroded electrical terminals in the MAF Sensor circuit, Faulty MAF Sensor

P0102 — The Mass Airflow Sensor (MAF) Sensor is unplugged or the wiring is damaged, Loose or corroded electrical terminals in the MAF Sensor circuit, Faulty MAF Sensor

Detailed page for trouble code P0102.

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P0102

AUDI P — Powertrain

The Mass Airflow Sensor (MAF) Sensor is unplugged or the wiring is damaged, Loose or corroded electrical terminals in the MAF Sensor circuit, Faulty MAF Sensor

Brand: AUDI
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
Repair manuals

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Code

P0102

Generic P — Powertrain

Mass or Volume Air Flow Sensor A Circuit Low

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
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Code

P0102

GWM P — Powertrain

- Low air mass meter reading

Brand: GWM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
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Code

P0102

HUMMER P — Powertrain

Mass Air Flow (MAF) Sensor Circuit Low Frequency

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
Repair manuals

Manual library for HUMMER

138

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Code

P0102

ISUZU P — Powertrain

Mass Air Flow Circuit Low Input

Brand: ISUZU
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
Repair manuals

Manual library for ISUZU

157

Browse 157 ISUZU manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

ISUZU

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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Code

P0102

LAND ROVER P — Powertrain

Low input from the air flow circuit in mass or volume

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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Code

P0102

MITSUBISHI P — Powertrain

AFS low input

Brand: MITSUBISHI
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • MAF sensor unplugged or connector not fully seated
  • Corroded, bent or loose terminals at MAF connector
  • Open or shorted wiring in MAF signal, power or ground circuits
  • Blown fuse or poor power/ground feed to the MAF
  • Failed or contaminated MAF sensor element
  • PCM input fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Rough idle, hesitation, stalling or poor throttle response
  • Reduced engine power or limp mode
  • Hard starting or no start in severe cases
  • Poor fuel economy; long-term fuel trim indicating lean condition
  • Surging or inconsistent idle

What to check

  • Read stored freeze-frame data and confirm P0102 is current or intermittent
  • Visually inspect MAF connector, terminals and wiring for damage or corrosion
  • Ensure MAF connector is fully seated and locking tab engaged
  • Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
  • Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
  • Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

  • Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
  • Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
  • Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
  • Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
  • Reference/power supply commonly ~5 V (verify per vehicle service data)

Diagnostic algorithm

  1. Verify the DTC and review freeze-frame and pending codes. Note operating conditions when fault set.
  2. Perform a visual inspection: check MAF connector, wiring harness, pins and clip for corrosion, bent pins, or contamination.
  3. With ignition ON, measure reference/power supply and ground at the MAF connector. Confirm proper supply voltage and a good ground.
  4. Start engine and monitor MAF signal (voltage or frequency) at the sensor while revving. Compare to expected behavior — signal should increase with RPM.
  5. Back-probe and wiggle harness to try to reproduce the fault. If signal drops to low or intermittent, isolate wiring fault.
  6. Check continuity from MAF signal/power/ground pins to PCM; look for opens or shorts to ground/power. Repair any wiring faults found.
  7. Inspect and clean or replace air filter and inspect intake tract for restrictions or leaks that could cause abnormal readings.
  8. If wiring and supply are good but signal remains abnormally low, test or replace the MAF sensor. If available, substitute a known-good MAF or bench-test per manufacturer specs.
  9. After repair, clear codes, perform a road test and recheck for reappearance of P0102. If intermittent, monitor live data over various conditions.
  10. Safety: avoid contact with moving engine parts and follow vehicle manufacturer electrical safety procedures when back-probing connectors.

Likely causes

  • Disconnected or loose MAF connector
  • Damaged wiring harness (open/short to ground) between MAF and PCM
  • Corroded or poor ground at sensor
  • Faulty MAF sensor
  • Contaminated MAF sensing element (oil/silicone/dirty)
  • Blown fuse or bad power supply to MAF

Fault status

⚠️ Status
P0102 — Mass Air Flow Circuit Low Input: PCM detected a MAF sensor signal lower than expected (low voltage, low frequency, or no signal). Possible causes include unplugged connector, damaged wiring, poor terminal connection, blown fuse, contaminated or failed MAF sensor, or PCM input fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

P0100 P0101 P0103 P0110 P0171 P0174
406

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