Code
P0372
GWM
P — Powertrain
- The number of pulses of the timer signal A is below the norm
AI status
Completed
Completed
100%
Causes
- Faulty cam/crank position sensor A (Hall or VR)
- Damaged or missing teeth on tone/reluctor wheel (timing wheel)
- Disconnected, corroded, damaged or shorted wiring/connectors for sensor A
- Sensor reference power, ground or signal circuit open/poor connection
- Timing belt/chain jumped or slipped (mechanical timing changed)
- Intermittent connector contact due to vibration or water ingress
Symptoms
- Malfunction Indicator Lamp (MIL) on
- Difficult cranking, no-start or intermittent no-start
- Rough idle, misfires or hesitation under load
- Reduced engine power and poor drivability
- Irregular tachometer reading or stalling
- Possible poor fuel economy or backfiring
What to check
- Read and record freeze frame and all stored codes; note engine RPM when code set
- Check related codes (crank/cam sensors, correlation codes, misfire codes)
- Visually inspect sensor A connector, wiring harness and engine grounds for damage or corrosion
- Inspect tone/reluctor wheel (cam or crank) for missing/bent teeth or physical damage
- Measure sensor supply voltage and ground with ignition ON
- Backprobe signal wire and check for pulse waveform while cranking (use oscilloscope preferred)
Signal parameters
- Expected waveform: regular pulses corresponding to engine RPM (square wave for Hall sensors; sinusoidal/AC for VR sensors)
- Pulse count: should match engine design (e.g., pulses per revolution or per camshaft turn) — compare to service data
- Voltage levels (typical): Hall sensor ~0–5 V square wave (low 2.5 V); VR sensor AC amplitude increases with RPM (should be measurable >0.2 V AC at cranking)
- Frequency: proportional to engine speed — verify pulses are present at cranking and idle
- Pulse timing: consistent spacing; no dropped or irregular pulses
Diagnostic algorithm
- Connect a scan tool and confirm P0372 is current; record freeze frame and related codes (P0335, P0340, P0016, etc.).
- Visually inspect sensor A, its connector and harness for damage, corrosion, loose pins or oil/water contamination. Repair as needed.
- Inspect the tone/reluctor wheel (cam or crank target) for missing or damaged teeth and correct mechanical issues if found.
- With ignition ON (engine OFF) verify sensor reference power and ground at the connector. Repair supply/ground faults before further testing.
- Backprobe sensor signal wire and observe waveform while cranking using an oscilloscope. Look for missing pulses, low amplitude, excessive noise or intermittent signal. For VR sensors check AC voltage; for Hall sensors check 0–5 V square wave.
- If signal is absent or abnormal, measure sensor resistance and compare with specification. Replace the sensor if out of spec or if waveform indicates failure.
- Check continuity and resistance of the signal wiring between sensor and ECU; repair any opens/shorts, and inspect shielding/grounding if interference suspected.
- If wiring and sensor test good but pulses are missing or timing looks incorrect, inspect/verify mechanical timing (timing belt/chain/cam timing). Repair mechanical timing issues and re-test.
- After repairs clear codes and perform a cranking/road test to confirm pulses return to expected counts and the code does not reappear.
- If all wiring, sensors and mechanical timing are good and the fault persists, consider ECU input circuit fault and follow manufacturer procedures for ECU testing/repair.
Likely causes
- Failed cam/crank position sensor A
- Wiring harness open/short at sensor or chafed under intake/bodywork
- Damaged/missing teeth on the sensor target wheel
- Connector corrosion or pin damage at sensor or ECU
- Timing chain/belt skipped a tooth (mechanical)
Fault status
Status
Timer signal A pulse count below threshold — signal missing or weak from timing sensor A. Check sensor, target wheel and associated wiring; consider timing chain/belt slip or ECU input fault.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
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