P0374 code meaning
Timing Reference High Resolution Signal A No Pulses
Powertrain system Generic code P03xx codes Check engine light
What P0374 means
Some diesel systems give the injection control a finely divided angle signal in addition to the normal reference signal – the high resolution signal. By its J2012 name P0374 means signal A delivers no pulses at all although the engine turns. GM's 2004 Duramax LB7 uses the code differently, for a plausibility fault: the injector driver module evaluates the 57X crank signal and reports it as implausible over CAN; from 60 rpm, 100 of 120 samples of 31.6 ms set the code, in the first trip. GM's 6.5-litre diesel with the optical sensor in the injection pump reports all faults of its high resolution track under P0370. Without the fine signal the module falls back to coarser timing, so the engine loses power and may run roughly or start poorly.
P0374 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 P0374
- Check engine light on
- Loss of power (limp-home fuelling)
- Rough running, hard starting, smoke
Common causes of P0374
- Most likelySensor (pump or crankshaft) faulty or dirty
- PossibleLoose contact or interference in the signal wire
- PossibleSensor disc or tone wheel damaged
- Less likelyInjector driver module or engine 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 moduleCrankshaft position sensor
What each part of P0374 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. |
| 74 | The exact fault in that area. |
What to do next
- Note P0374 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 P0374
What does P0374 mean?
P0374 means "Timing Reference High Resolution Signal A No Pulses". Some diesel systems give the injection control a finely divided angle signal in addition to the normal reference signal – the high resolution signal. It is a generic code, so it means the same on every make.
Is it safe to drive with P0374?
Drive gently and only to a workshop. With P0374 the car can go into limp mode (reduced power) to protect itself.
Will P0374 fail an emissions test?
Yes, it can. P0374 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 P0374 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0374 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.