HomeTrouble CodesP0371

P0371 — Timing Reference High Resolution Signal Too Many Pulses

Generic OBD-II · all makesPowertrain (engine & transmission)

The P0371 code indicates that the engine control module (ECM) has detected more pulses than expected from the high-resolution timing reference sensor. This suggests a discrepancy between the actual crankshaft or camshaft rotation and the signal being reported to the computer.

Symptoms

What causes it — most likely first

1. Faulty Crankshaft Position Sensor

The sensor may have internal electrical failure or contamination, leading to erratic signal pulses.

2. Damaged Reluctor Wheel

A bent, loose, or fouled tone ring/reluctor wheel can create extra pulses as it passes the sensor.

3. Timing Chain or Belt Issues

A stretched timing chain or a jumped belt can cause mechanical misalignment, altering the pulse timing.

4. Wiring Harness Interference

Frayed wires or poor shielding can introduce electromagnetic noise, which the ECM interprets as extra pulses.

5. ECM Internal Failure

A failure in the signal processing circuit of the engine control module, though this is rare.

How it's diagnosed

  1. Scan the ECM for all stored and pending codes to identify related sensor faults.
  2. Inspect the timing reference sensor wiring for chafing, shorts, or corrosion.
  3. Remove the sensor and inspect the tip for metal shavings or debris.
  4. Inspect the reluctor wheel for missing teeth, debris, or physical damage.
  5. Verify mechanical timing alignment using the engine's specified timing marks.
  6. Use an oscilloscope to analyze the high-resolution signal waveform for noise or irregular pulses.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make

Frequently asked

Can this code be caused by a bad spark plug?

No, P0371 is related to the timing reference signal from the crankshaft or camshaft, not the combustion process or ignition system.

Is this a mechanical or electrical failure?

It can be both; while it often manifests as a sensor failure (electrical), it can also be caused by a stretched timing chain or damaged reluctor wheel (mechanical).

Should I replace the PCM/ECM to fix this code?

No. While the PCM is listed as a potential cause, it is rarely the source of P0371. Most cases are resolved by addressing sensor, wiring, or mechanical timing issues.