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P0375 OBD-II Trouble Code: Timing Reference High Resolution Signal B Malfunction

check engine light

P0375 code definition

If a PCM stores the P0375 code, it means it has detected a problem with the high resolution timing reference signal. “Signal B” is a reference to the location of the system circuitry and not a particular component.

What the P0375 code means

Your vehicle was made with an optical sensor that is responsible for providing high resolution signals to the PCM (Powertrain Control Module). Specifically, it does this by counting pulses on the vehicle’s sensor disk, installed in the injection pump.

These high resolution inputs are one of the most important the PCM receives as it directly affects the module’s ability to fuel timing and control. For every pump cam pulse, the number of pulses detected is counted and compared to how many should have occurred. If the number counted is abnormal, then the PCM will store the P0375 trouble code.

What causes the P0375 code?

The majority of the time, the P0375 code is stored because of one of the following common causes:

  • A faulty camshaft
  • A defective crankshaft
  • Faulty distributor position sensors

This last reason is especially likely if your vehicle is rear-wheel drive and high in mileage. Other reasons that could be responsible involve the vehicle’s wiring. Damaged, corroded or otherwise faulty wiring and/or connectors could also trigger the code.

Although it’s happened, PCM failure is very unlikely and an extremely rare reason for P0375 to be stored.

What are the symptoms of the P0375 code?

Unfortunately, one of the biggest challenges with the P0375 code is that although it can have potentially serious symptoms, it can also be very difficult to detect until it’s too late and you’re facing expensive repairs. Furthermore, the Check Engine Light may not even come on until at least a few failure cycles occur (this differs by model).

More serious symptoms are things like engines misfiring or spark knocking. This last symptom occurs when your fuel simply detonates at random times. Aside from the noise you’ll hear, it also means that your fuel efficiency is seriously suffering.

Even if spark knocks don’t occur, poor fuel efficiency is another sign that your vehicle may be suffering from issues related to P0375.

How does a mechanic diagnose the P0375 code?

A qualified mechanic will use a scanner to grab the code from your vehicle’s PCM. They will probably also use a tachometer to see what happens when your vehicle is cranked.

If they do this and no RPM signal is registered, the mechanic will then inspect the vehicle’s crankshaft position sensor, crankshaft gear, and sensor connector for any indication that damage has occurred which would lead to code P0375. Wires and other electrical components will be examined for the same reason.

If those steps fail to satisfactorily diagnose the problem, they’ll use an oscilloscope to test the CPS signal wire of your vehicle for adequate waveforms during every engine resolution.

Common mistakes when diagnosing the P0375 code

When mechanical distributor failure is responsible for causing P0375, a fairly common mistake during the diagnosis process is immediately blaming the camshaft, distributor sensors or crankshaft. As a result, they sometimes get replaced for no reason.

How serious is the P0375 code?

Given how severe some of the worst symptoms of problems connected to P0375 can be, this is one you’ll want to get checked by a professional mechanic right away. Although it’s not life-threatening, you’d hate for this problem to progress into something that could become dangerous.

What repairs can fix the P0375 code?

Your mechanic may do any of the following to clear P0375:

Additional comments for consideration regarding the P0375 code

Need help with a P0375 code?

If your vehicle isn’t working correctly because of issues connected to the P0375 code, YourMechanic is here to help. Just fill out our online form to set an appointment or receive a free quote. You can also call us at 1-800-701-6230 to speak with one of our service advisors.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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