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P0370 OBD-II Trouble Code: Timing Reference High Resolution Signal A Malfunction

Check Engine Lights

P0370 code definition

The P0370 code indicates that there is an error in the resolution signal in the optical sensor on your car’s timing system.

What the P0370 code means

The P0370 code means that the optical sensor has missed a number of high resolution pulses in correlation to cam reference pulses. These pulses provide the PCM with information needed to ensure fuel is delivered correctly, and that the right air mixture is provided for combustion.

What causes the P0370 code?

It is possible for a number of different conditions to cause the P0370 code to set, including the following:

  • A short or open in the wiring harness to the timing reference optical sensor
  • Damage to your car’s PCM (powertrain control module)
  • A fault in the timing reference optical sensor
  • A corroded or poor connection at the timing reference optical sensor

What are the symptoms of the P0370 code?

Generally, you will not notice many drivability issues if the P0370 code sets. The most likely will be the Check Engine Light turning on. However, it is also possible that you will notice reduced fuel mileage and rough engine operation.

How does a mechanic diagnose the P0370 code?

Diagnosing the P0370 code will require the mechanic to first connect an OBD II scanner to the car’s communication port, which is usually located under the dash on the driver side. The technician will read the codes stored in the computer and then clear them. It will be necessary to test drive the vehicle to see if the code resets. If the code does reset, the mechanic will then move on to further diagnostic steps.

The wiring harness for the timing reference optical sensor will need to be checked for damage or breakage. If nothing is found wrong with the harness, the connections will be checked. The sensor itself may also need to be cleaned and tested. This may require removing the sensor from the car in order for an accurate test to be conducted.

Common mistakes when diagnosing the P0370 code

Many technicians make the mistake of assuming that the underlying problem is the sensor itself and replacing it without completing a full diagnostic. While the sensor is often the culprit, it is also possible for the problem to be completely unrelated to the sensor (wiring harness, connections, etc.). Therefore, a full diagnostic should be performed to rule out any other possibilities.

How serious is the P0370 code?

The P0370 code might not create significant drivability problems initially. It may not even cause any symptoms beyond the Check Engine Light illuminating. However, because the reference signal from the optical sensor is crucial to the PCM’s ability to meter fuel flow, it is very important to have it repaired as quickly as possible.

What repairs can fix the P0370 code?

The most common repair for the P0370 code is replacing a failed reference optical sensor. However, other fixes may be needed depending on the actual underlying cause of the fault, including:

Need help with a P0370 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

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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