P0371 Timing Reference High Resolution Signal A Too Many Pulses

P0371 points to too many pulses in Timing Reference High Resolution Signal A. The controller is receiving extra transitions or noise in the high-resolution timing signal.

Code details

Generic OBD-II · P0

System: Ignition / Misfire
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not adjust timing or replace modules before checking signal noise, shielding, and physical trigger wheel condition.

Symptoms of P0371

Rough idle, shaking, or a stumble under acceleration.
A flashing check-engine light during an active misfire.
Power loss and higher fuel consumption.

Common causes of P0371

Worn spark plugs, ignition coils, or plug wires.
Fuel-delivery problems — injectors, pressure, or a lean/rich mixture.
Vacuum leaks, low compression, or a mechanical fault in that cylinder.

Useful checks before replacing parts

Review RPM spikes, high-resolution signal A pulse count, crank signal quality, freeze-frame conditions, and electrical noise or interference codes.
Inspect shielding, sensor air gap, damaged reluctor teeth, loose sensor mounting, wiring near ignition components, poor grounds, and connector corrosion.
Scope the signal to identify double-triggering, noise, vibration-induced pulses, or a distorted waveform.

Related OBD-II codes

These nearby ignition / misfire entries can help compare wording and pin down the fault area.