P0370Timing Reference High Resolution Signal A
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Some diesel systems give the injection control a finely divided angle signal in addition to the normal reference signal, to time and meter injection precisely – the high resolution signal. GM's 6.5-litre diesel (1997) had an optical sensor in the injection pump that delivers a high resolution track and one cam reference pulse per cylinder; P0370 is set if more than 8 consecutive cam pulses pass without progress on the high resolution counter, in the first trip. The engine then runs on backup fuelling with reduced power, and injection timing control is suspended. On the 2004 Duramax LB7 the injector driver module evaluates the 57X crank signal and reports 'no crank signal' over CAN; from 60 rpm, 100 of 120 samples sets P0370, also in the first trip. Petrol engines practically do not use the code.
- What you may notice
- Check engine light on
- Loss of power (limp-home fuelling)
- Rough running, hard starting, smoke
- Stalling possible
- Likely causes
- LikelyOptical sensor in the injection pump faulty (6.5-litre)
- PossibleWiring or connector between pump or sensor and module
- PossibleCrankshaft sensor or tone wheel (LB7: 57X signal)
- RareInjector driver module, engine module or CAN communication
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.