P0371 code meaning
Timing Reference High Resolution Signal A Too Many Pulses
Powertrain system Generic code P03xx codes Check engine light
What P0371 means
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. P0371 means signal A delivers more pulses than expected within the reference window – for example more high resolution pulses per reference pulse than the nominal ratio, which on GM's 6.5-litre diesel is 64 ± 4 per cam pulse; the usual cause is interference pulses. No manufacturer document available to us uses P0371: 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.
P0371 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0371
- Check engine light on
- Loss of power (limp-home fuelling)
- Rough running, hard starting, smoke
Common causes of P0371
- Most likelySensor faulty or dirty
- PossibleLoose contact or interference in the signal wire
- PossibleSensor disc or tone wheel damaged
- Less likelyEngine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
High resolution timing sensorInjection pumpSensor wiringEngine control module
What each part of P0371 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| 71 | The exact fault in that area. |
What to do next
- Note P0371 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0371
What does P0371 mean?
P0371 means "Timing Reference High Resolution Signal A Too Many Pulses". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0371?
Drive gently and only to a workshop. With P0371 the car can go into limp mode (reduced power) to protect itself.
Will P0371 fail an emissions test?
Yes, it can. P0371 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0371 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0371 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.