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P0690 OBD-II Trouble Code: ECM/PCM Power Relay Sense Circuit High

check engine light

P0690 trouble code definition

A P0690 trouble code is related to a vehicle’s engine control module (ECM) or powertrain control module and its direct power supply from the battery.

What the P0690 code means

P0690 is an OBD-II generic code for a high voltage problem with the power supply to the ECM/PCM. This means the vehicle’s computer is not receiving voltage that is within the manufacturer’s parameters.

What causes the P0690 code?

A P0690 code can have a variety of causes, but the most common are:

What are the symptoms of the P0690 code?

A P0690 code will typically have night and day symptoms. Either there will be just a Check Engine Light, or the vehicle will simply not start.

How does a mechanic diagnose the P0690 code?

Because there are a number of potential causes for a P0690, your mechanic will start easy and clear the code and reset the ECM/PCM. If the code does not return, your mechanic will ensure all electrical connections for the battery and ECM/PCM are tight and it good condition - repairing as needed. Engine grounds will also be checked and cleaned as needed. If the code returns however, the ECM/PCM relay will need to be tested using a digital multi meter. If the relay is faulty, it will need to be replaced. In some cases, the ECM/PCM will need to be either reflashed or replaced.

Common mistakes when diagnosing the P0690 code

Because ECM/PCM replacements can be costly, this isn’t the best first move to make when dealing with a P0690. It’s important to test as many components as necessary and reset the ECM/PCM as needed.

How serious is the P0690 code?

This can either be serious or not so serious, and it depends on the condition of the vehicle when a P0690 is present. If there is a no-start condition, the problem could be more severe than if the code is illuminated and driving is normal.

What repairs can fix the P0690 code?

The most common repairs for a P0690 are as follows:

  • Replacing the ECM/PCM relay
  • Repairing ECM/PCM power wiring
  • Replacing ECM/PCM fuses
  • Replacing damaged battery cables
  • Replacing the ECM/PCM

Additional comments for consideration regarding the P0690 code

If a P0690 is present, you may have other codes accompanying it. Check the order in which these codes come up on a OBD-II scanner as the ones higher above may be the route cause of the P0690.

Need help with a P0690 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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