Code
P0344
Generic
P — Powertrain
Camshaft Position Sensor A Circuit Intermittent Bank 1 or Single Sensor
AI status
Completed
Completed
100%
Causes
- Damaged wiring (chafing, broken conductor, corrosion) or poor connector contact to the camshaft position sensor
- Failed camshaft position sensor (intermittent internal fault)
- Intermittent sensor reference or power supply (loss of 5V or ground)
- Faulty ECM input or intermittent ECU grounding/power issue
- Damaged or worn tone/reluctor wheel or timing components (cam reluctor, cam phaser, timing chain/belt)
- Interference from nearby high-voltage ignition components or aftermarket devices
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated intermittently
- Intermittent rough idle, stumbling, or hesitation under load
- Intermittent misfires and/or reduced engine performance
- Hard starting or no-start conditions in some instances
- Loss of synchronization codes or cam/crank correlation-related symptoms (e.g., limp mode)
What to check
- Read and record freeze frame and complete scan tool data; note other related codes (crankshaft sensor, misfire codes)
- Visually inspect sensor connector and wiring for corrosion, bent pins, damaged insulation, or poor retention
- Wiggle-test wiring and connector while monitoring live cam sensor signal to reproduce the fault
- Inspect cam reluctor, camshaft phaser, and timing chain/belt condition for damage or excessive play
- Verify sensor mounting is secure and air gap/setback is correct per service data
- Check ECM power and ground circuits for corrosion, loose connections, or intermittent supply
Signal parameters
- Hall/variable electronic sensor: digital square wave, 0–5 V (0 V low, ≈5 V high) with ~50% duty cycle; frequency proportional to engine speed
- Variable reluctor (magnetic) sensor: AC sine/peaked waveform; amplitude increases with RPM (typical low-RPM amplitude 0.2–1.5 VAC)
- Cam produces one or a few pulses per two crank revolutions (depends on engine design); timing reference should remain steady relative to crank
- Intermittent faults may show dropped pulses, truncated edges, noisy baseline, or voltage spikes/transients
Diagnostic algorithm
- Verify the fault: clear DTCs and attempt to reproduce. Note conditions when code sets (cold start, hot, vibration, RPM range).
- Scan for related codes (P0335, P0340, misfire codes) and check freeze-frame data to correlate RPM and engine state when the fault occurred.
- Perform a visual inspection of the cam sensor, connector, and wiring. Repair obvious damage, secure connectors, and apply dielectric grease if appropriate.
- Back-probe the sensor connector with a multimeter/scan tool: verify reference voltage (usually 5 V or switched 12 V as specified), ground continuity, and signal presence while cranking and at idle.
- If circuit power/ground are OK, capture a live signal with an oscilloscope. Look for missing pulses, noise, voltage spikes, incorrect amplitude, or intermittent dropouts. Wiggle the harness and connectors to try to reproduce.
- If the signal is absent or intermittent and wiring checks out, swap or bench-test the cam sensor (per manufacturer procedure) or substitute a known-good sensor.
- Inspect timing components (reluctor wheel, cam phaser, timing chain/belt) for damage or excessive slack if the signal waveform shows irregular timing or missing teeth/pulses.
- If wiring and sensor test good but intermittent signal persists, check ECM input circuitry and associated grounds/power. Repair or replace as required.
- After repairs, clear codes and road-test across the operating range that previously reproduced the issue. Re-scan to confirm code does not return.
Likely causes
- Intermittent connector corrosion or loose pin at cam sensor
- Broken or internally fractured sensor lead that moves with vibration
- Contaminated or oil-fouled sensor causing intermittent contact
- Faulty sensor electronics that fail intermittently under temperature/vibration
- Wiring harness damage at flex points near the head or timing cover
Fault status
Status
Intermittent signal detected from Camshaft Position Sensor A (Bank 1/single). Possible loose connector, damaged wiring, faulty sensor, or timing/reluctor problem causing intermittent cam signal.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0344
GWM
P — Powertrain
- Camshaft Position Sensor Malfunction
AI status
Completed
Completed
100%
Causes
- Damaged wiring (chafing, broken conductor, corrosion) or poor connector contact to the camshaft position sensor
- Failed camshaft position sensor (intermittent internal fault)
- Intermittent sensor reference or power supply (loss of 5V or ground)
- Faulty ECM input or intermittent ECU grounding/power issue
- Damaged or worn tone/reluctor wheel or timing components (cam reluctor, cam phaser, timing chain/belt)
- Interference from nearby high-voltage ignition components or aftermarket devices
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated intermittently
- Intermittent rough idle, stumbling, or hesitation under load
- Intermittent misfires and/or reduced engine performance
- Hard starting or no-start conditions in some instances
- Loss of synchronization codes or cam/crank correlation-related symptoms (e.g., limp mode)
What to check
- Read and record freeze frame and complete scan tool data; note other related codes (crankshaft sensor, misfire codes)
- Visually inspect sensor connector and wiring for corrosion, bent pins, damaged insulation, or poor retention
- Wiggle-test wiring and connector while monitoring live cam sensor signal to reproduce the fault
- Inspect cam reluctor, camshaft phaser, and timing chain/belt condition for damage or excessive play
- Verify sensor mounting is secure and air gap/setback is correct per service data
- Check ECM power and ground circuits for corrosion, loose connections, or intermittent supply
Signal parameters
- Hall/variable electronic sensor: digital square wave, 0–5 V (0 V low, ≈5 V high) with ~50% duty cycle; frequency proportional to engine speed
- Variable reluctor (magnetic) sensor: AC sine/peaked waveform; amplitude increases with RPM (typical low-RPM amplitude 0.2–1.5 VAC)
- Cam produces one or a few pulses per two crank revolutions (depends on engine design); timing reference should remain steady relative to crank
- Intermittent faults may show dropped pulses, truncated edges, noisy baseline, or voltage spikes/transients
Diagnostic algorithm
- Verify the fault: clear DTCs and attempt to reproduce. Note conditions when code sets (cold start, hot, vibration, RPM range).
- Scan for related codes (P0335, P0340, misfire codes) and check freeze-frame data to correlate RPM and engine state when the fault occurred.
- Perform a visual inspection of the cam sensor, connector, and wiring. Repair obvious damage, secure connectors, and apply dielectric grease if appropriate.
- Back-probe the sensor connector with a multimeter/scan tool: verify reference voltage (usually 5 V or switched 12 V as specified), ground continuity, and signal presence while cranking and at idle.
- If circuit power/ground are OK, capture a live signal with an oscilloscope. Look for missing pulses, noise, voltage spikes, incorrect amplitude, or intermittent dropouts. Wiggle the harness and connectors to try to reproduce.
- If the signal is absent or intermittent and wiring checks out, swap or bench-test the cam sensor (per manufacturer procedure) or substitute a known-good sensor.
- Inspect timing components (reluctor wheel, cam phaser, timing chain/belt) for damage or excessive slack if the signal waveform shows irregular timing or missing teeth/pulses.
- If wiring and sensor test good but intermittent signal persists, check ECM input circuitry and associated grounds/power. Repair or replace as required.
- After repairs, clear codes and road-test across the operating range that previously reproduced the issue. Re-scan to confirm code does not return.
Likely causes
- Intermittent connector corrosion or loose pin at cam sensor
- Broken or internally fractured sensor lead that moves with vibration
- Contaminated or oil-fouled sensor causing intermittent contact
- Faulty sensor electronics that fail intermittently under temperature/vibration
- Wiring harness damage at flex points near the head or timing cover
Fault status
Status
Intermittent signal detected from Camshaft Position Sensor A (Bank 1/single). Possible loose connector, damaged wiring, faulty sensor, or timing/reluctor problem causing intermittent cam signal.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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Code
P0344
HUMMER
P — Powertrain
Camshaft Position Sensor Circuit Intermittent
AI status
Completed
Completed
100%
Causes
- Damaged wiring (chafing, broken conductor, corrosion) or poor connector contact to the camshaft position sensor
- Failed camshaft position sensor (intermittent internal fault)
- Intermittent sensor reference or power supply (loss of 5V or ground)
- Faulty ECM input or intermittent ECU grounding/power issue
- Damaged or worn tone/reluctor wheel or timing components (cam reluctor, cam phaser, timing chain/belt)
- Interference from nearby high-voltage ignition components or aftermarket devices
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated intermittently
- Intermittent rough idle, stumbling, or hesitation under load
- Intermittent misfires and/or reduced engine performance
- Hard starting or no-start conditions in some instances
- Loss of synchronization codes or cam/crank correlation-related symptoms (e.g., limp mode)
What to check
- Read and record freeze frame and complete scan tool data; note other related codes (crankshaft sensor, misfire codes)
- Visually inspect sensor connector and wiring for corrosion, bent pins, damaged insulation, or poor retention
- Wiggle-test wiring and connector while monitoring live cam sensor signal to reproduce the fault
- Inspect cam reluctor, camshaft phaser, and timing chain/belt condition for damage or excessive play
- Verify sensor mounting is secure and air gap/setback is correct per service data
- Check ECM power and ground circuits for corrosion, loose connections, or intermittent supply
Signal parameters
- Hall/variable electronic sensor: digital square wave, 0–5 V (0 V low, ≈5 V high) with ~50% duty cycle; frequency proportional to engine speed
- Variable reluctor (magnetic) sensor: AC sine/peaked waveform; amplitude increases with RPM (typical low-RPM amplitude 0.2–1.5 VAC)
- Cam produces one or a few pulses per two crank revolutions (depends on engine design); timing reference should remain steady relative to crank
- Intermittent faults may show dropped pulses, truncated edges, noisy baseline, or voltage spikes/transients
Diagnostic algorithm
- Verify the fault: clear DTCs and attempt to reproduce. Note conditions when code sets (cold start, hot, vibration, RPM range).
- Scan for related codes (P0335, P0340, misfire codes) and check freeze-frame data to correlate RPM and engine state when the fault occurred.
- Perform a visual inspection of the cam sensor, connector, and wiring. Repair obvious damage, secure connectors, and apply dielectric grease if appropriate.
- Back-probe the sensor connector with a multimeter/scan tool: verify reference voltage (usually 5 V or switched 12 V as specified), ground continuity, and signal presence while cranking and at idle.
- If circuit power/ground are OK, capture a live signal with an oscilloscope. Look for missing pulses, noise, voltage spikes, incorrect amplitude, or intermittent dropouts. Wiggle the harness and connectors to try to reproduce.
- If the signal is absent or intermittent and wiring checks out, swap or bench-test the cam sensor (per manufacturer procedure) or substitute a known-good sensor.
- Inspect timing components (reluctor wheel, cam phaser, timing chain/belt) for damage or excessive slack if the signal waveform shows irregular timing or missing teeth/pulses.
- If wiring and sensor test good but intermittent signal persists, check ECM input circuitry and associated grounds/power. Repair or replace as required.
- After repairs, clear codes and road-test across the operating range that previously reproduced the issue. Re-scan to confirm code does not return.
Likely causes
- Intermittent connector corrosion or loose pin at cam sensor
- Broken or internally fractured sensor lead that moves with vibration
- Contaminated or oil-fouled sensor causing intermittent contact
- Faulty sensor electronics that fail intermittently under temperature/vibration
- Wiring harness damage at flex points near the head or timing cover
Fault status
Status
Intermittent signal detected from Camshaft Position Sensor A (Bank 1/single). Possible loose connector, damaged wiring, faulty sensor, or timing/reluctor problem causing intermittent cam signal.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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