P0377Timing Reference High Resolution Signal B Too Few Pulses
- 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 – the high resolution signal – for precise injection timing and metering. P0377 means a second high resolution signal, B, delivers fewer pulses than expected within the reference window; it is checked in the same way as signal A (P0370 ff). No manufacturer with a separate signal B was found – GM's diesels with a high resolution signal (6.5-litre, Duramax LB7) only have signal A, and Ford and GM 2014–2019 do not use the codes. The description therefore follows the J2012 name, the analogy to signal A and CARB's monitoring requirement for crank angle sensors. Typically the engine loses power and runs roughly.
- What you may notice
- Check engine light on
- Loss of power (limp-home fuelling)
- Rough running, hard starting, smoke
- Likely causes
- LikelySensor faulty or dirty
- PossibleLoose contact or interference in the signal wire
- RareSensor disc or tone wheel damaged
- RareEngine module
- 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.