What the P0657 code means?
The PCM and the vehicles other control modules are constantly performing self-checks and self-monitoring to ensure that the PCM is functioning efficiently and properly. The PCM does this through checks of output signals, internal circuits, and checks on its internal memory status. If there's a malfunction during this monitoring process, the PCM will store the P0657 code after a predetermined number of drive cycles. Some vehicles will require up to eight cycles of malfunctions, while others will require fewer.
What causes the P0657 code?
1. Open/chafed wire
2. Water intrusion
3. Melted/broken connector
4. Short to power
What are the symptoms of the P0657 code?
Symptoms may include a stored trouble code, a hard or no start condition, rough running engine, decreased fuel efficiency, engine misfire, and a general lack of power. If this code is stored, and a service engine soon lamp has not yet been illuminated, the code may be shown as pending.
Common mistakes when diagnosing the P0657 code:
Symptoms and stored codes that are present as a reaction to a communication failure are often misdiagnosed and repaired as the cause of the problem. Obviously, this leads to an unsuccessful repair.
What repairs can fix the P0657 code?
Though the problem causing this code will almost always be a shorted or open circuit, there are a few different repairs that may fix it, including:
1. Securing and tightening PCM connectors and/or ground wires.
2. Repairing or replacing the PCM wiring harness.
3. Reprogramming the PCM.
4. Replacing the PCM.