P0379 Timing Reference High Resolution Signal B No Pulses

P0379 indicates no pulses from Timing Reference High Resolution Signal B. The controller is missing the expected B channel timing reference input.

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 continue no-start diagnosis without confirming why timing reference signal B has no pulses.

Symptoms of P0379

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 P0379

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

Check high-resolution signal B status, RPM data, crank and cam sync, spark and injector enable, freeze-frame data, and related timing codes.
Inspect sensor supply, ground, signal continuity, connector condition, trigger wheel or optical track damage, and controller input integrity.
Verify signal presence at the sensor and at the module to separate sensor, harness, trigger, and controller faults.

Related OBD-II codes

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