U0665 indicates that the powertrain control module (PCM) has lost communication with the fuel rail pressure sensor located on bank 2 of the engine. This prevents the PCM from receiving accurate fuel pressure data, which can affect engine performance and emissions.
The sensor itself may be internally shorted, open, or otherwise unable to transmit a signal to the PCM.
Corrosion, chafed wires, loose pins, or a broken harness can interrupt the signal or power/ground paths.
If the sensor does not receive proper voltage or a solid ground, the PCM will see a loss of communication.
A rare internal fault in the PCM’s sensor interface can prevent it from reading the sensor, though this is uncommon.
Noise or a temporary fault on the vehicle’s communication network can disrupt sensor data transmission.
Very rarely, corrupted PCM software may misinterpret sensor status; a calibrated update can resolve it.
No. PCM failure is a rare cause of U0665. The sensor, its wiring, or power/ground issues are far more common and should be investigated first.
Yes. Loss of proper voltage or ground at the sensor will prevent communication, causing the PCM to log a lost‑communication fault.
The vehicle may run poorly, lose power, or stall. Prolonged operation could lead to further engine or emissions issues, so repair is advised.
Clearing may temporarily turn off the light, but if the underlying fault isn’t fixed the code will return. Diagnose and repair the root cause before relying on a cleared code.