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Home / DTC / P1423 — Intake Air High Pressure Switch Circuit High Voltage

P1423 — Intake Air High Pressure Switch Circuit High Voltage

Detailed page for trouble code P1423.

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Code

P1423

BUICK P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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Code

P1423

CADILLAC P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
206

Browse 206 CADILLAC manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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Code

P1423

CHEVROLET P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
456

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Code

P1423

CHRYSLER P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
193

Browse 193 CHRYSLER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

CHRYSLER

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+100 karma for a short comment :)
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Code

P1423

GM P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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Code

P1423

GMC P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
Your experience will help others
+100 karma for a short comment :)
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Code

P1423

HUMMER P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
Repair manuals

Manual library for HUMMER

138

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Code

P1423

OLDSMOBILE P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1423

Other P — Powertrain

EGI Functionality Test Failed

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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Code

P1423

PLYMOUTH P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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Code

P1423

PONTIAC P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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Code

P1423

SATURN P — Powertrain

Intake Air High Pressure Switch Circuit High Voltage

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1423

SUBARU P — Powertrain

EVAP Vent Control High Input

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1423

VOLKSWAGEN P — Powertrain

Secondary Air Injection System Bank 1 Flow Too Low

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

Causes

  • Open or damaged wiring in the switch signal circuit
  • Short to battery positive (B+) on the signal wire
  • Corroded, bent or loose connector pins at switch or PCM
  • Failed intake air high pressure switch
  • Poor or missing reference ground or pull‑down in PCM
  • PCM internal input fault (rare)

Symptoms

  • Check Engine Light (MIL) illuminated
  • Possible reduced engine performance or limp mode depending on related control strategy
  • Stored diagnostic trouble code P1423 and possibly related intake/boost codes
  • No obvious mechanical noise or leak specific to this code

What to check

  • Read and record freeze frame data and all stored/related codes
  • Scan live data for intake air high pressure switch state and related sensors (MAP/boost)
  • Visually inspect switch connector and wiring for damage, corrosion, or pin push‑out
  • Backprobe signal wire with ignition ON to measure voltage at the switch and at the PCM
  • Check for continuity between switch signal pin and PCM signal pin and for shorts to B+ and to ground

Signal parameters

  • Typical system uses a pull‑up or reference; expected signal states commonly ~0.0–0.5 V for LOW (active) and ~4.5–5.0 V for HIGH (inactive)
  • Threshold switching often around 2–3 V (varies by model); code sets when PCM sees voltage above expected threshold in a condition requiring LOW
  • Open circuit or short to B+ will often present a steady high voltage near battery/reference voltage with ignition ON

Diagnostic algorithm

  1. Retrieve and record all codes, freeze frame and live data. Confirm P1423 is current and note related codes (MAP, boost, MAF).
  2. Visually inspect the intake air high pressure switch, its connector and wiring harness for damage, corrosion, heat chafe or pin issues. Repair any obvious damage.
  3. With ignition ON (engine OFF) backprobe the switch signal terminal: measure voltage between signal and ground. Compare voltage to expected signal parameters.
  4. Disconnect the switch connector and remeasure the voltage at the harness/PCM side. If voltage stays high, suspect wiring short to B+ or PCM pull‑up. If voltage changes to expected default, suspect the switch.
  5. Check continuity from the switch signal terminal to the PCM input terminal. Also check for short to battery positive and short to ground on the signal wire.
  6. If wiring and connector are good, bench‑test or replace the intake air high pressure switch per service manual instructions (or substitute a known good switch) and recheck signal and codes.
  7. If problem persists with a known good switch and wiring, test or replace the PCM input circuit only after verifying wiring and following manufacturer procedures.
  8. After repairs, clear codes, perform active tests (if available) and road test to confirm the fault does not return.

Likely causes

  • Connector corrosion or broken pin at the switch
  • Damaged insulation with short to B+ on the signal lead
  • Failed switch stuck in open/high state
  • Intermittent harness damage near moving components or heat source

Fault status

⚠️ Status
Intake Air High Pressure Switch Circuit High Voltage — PCM detected higher than expected voltage on the intake air high pressure switch input. Inspect wiring, connector and switch; repair as needed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0108 P0118 P0193 P0123 P1250 P0234
626

Browse 626 VOLKSWAGEN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

VOLKSWAGEN

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