Powertrain, generic · Ignition system or misfire

P0373 Timing Reference High Resolution Signal A Intermittent/Erratic Pulses

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Some diesel systems give the injection control a finely divided angle signal in addition to the normal reference signal – the high resolution signal – for precise injection timing and metering. P0373 means signal A delivers pulses with erratic spacing or with occasional dropouts – typical of a loose contact or electrical interference. No manufacturer document available to us uses P0373: GM's 6.5-litre diesel (optical sensor in the injection pump) reports all faults of its high resolution track under P0370 and the Duramax LB7 uses only P0370 and P0374. The description therefore follows the J2012 name, GM's description of the signal and CARB's monitoring requirement for crank angle sensors. Typically the engine loses power and runs roughly.

Likely causes

Sensor faulty or dirty
Loose contact or interference in the signal wire
Sensor disc or tone wheel damaged
Engine module

Symptoms

  • Check engine light on
  • Loss of power (limp-home fuelling)
  • Rough running, hard starting, smoke

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,500
Time1–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

high resolution timing sensorinjection pumpsensor wiringengine control module

Related codes

P0370P0371P0372P0374P0335

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.