HomeTrouble CodesU0650

U0650 — Lost Communication Exhaust Pressure Control Valve Sensorswitch

Generic OBD-II · all makesNetwork / communication

This diagnostic trouble code indicates the engine control module has lost communication with the exhaust pressure control valve sensor or switch. It typically points to an electrical interruption rather than a mechanical failure within the engine itself. The system cannot monitor or control exhaust backpressure due to this signal loss.

Symptoms

What causes it — most likely first

1. Damaged wiring or connectors at the valve

Heat and vibration near the exhaust often crack insulation or corrode terminals.

2. Blown fuse or lost power supply

The sensor circuit requires constant voltage which may be interrupted by a failed fuse.

3. Failed exhaust pressure control valve assembly

Internal electronics within the valve or sensor can fail due to extreme heat exposure.

4. Open or shorted communication circuit

The data wire connecting the component to the network may be broken or grounded.

5. Poor ground connection

Corrosion at the grounding point prevents the sensor from completing its circuit.

6. Internal control module fault

A failure within the PCM is possible but statistically rare compared to wiring or component faults.

How it's diagnosed

  1. Visually inspect wiring harness and connectors for physical damage or corrosion
  2. Verify fuse integrity and voltage supply at the component connector
  3. Check ground circuit continuity and resistance values
  4. Scan for additional network communication codes to isolate the circuit
  5. Test sensor data integrity using a diagnostic scan tool
  6. Evaluate control module connections only after peripheral circuits are cleared

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Will replacing the PCM fix this code?

No, this code is rarely caused by the computer; wiring or the valve itself is the usual cause.

Is it safe to drive with this code present?

Driving is not recommended as engine performance may be limited to protect the system.

What causes the communication to be lost?

Vibration, heat, and corrosion often damage the wiring or connectors near the exhaust system.

Does this require immediate repair?

Yes, because it affects emissions monitoring and engine management strategies.