P0688 OBD-II: ECM/PCM Power Relay Sense Circuit/Open
P0688 Severity
Should you fix P0688 yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P0688?
The engine computer (PCM) power relay controls battery voltage to the PCM. If the PCM detects an incorrect voltage signal from the power relay, it will set code P0688.
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