U0650Lost Communication With Exhaust Pressure Control Valve A Sensor/Switch
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- The exhaust pressure control valve is a throttle flap in the exhaust that diesels use to raise back pressure and exhaust temperature, for example during warm-up or filter regeneration. In GM's 2025 diesel table 25OBDG04B this flap is called ETV and reports its position by SENT. U0650 is stored when 480 of 600 checks at 6.25 ms intervals find the position protocol steady low or high with outdated data, a message error, or stalled counters, with relay voltage above 11 V and the engine past cranking. Being Type A, it lights the MIL during the first faulty trip. The same table keeps the drive circuit (P0475) and tracking errors above 10 % (P0476) apart; analog sensor faults are P048B to P048F, valve B has U067E.
- What you may notice
- MIL on from the first trip
- Particulate filter regeneration delayed or blocked
- Slower warm-up in cold weather
- Likely causes
- LikelyWiring at the exhaust flap damaged by heat
- PossibleConnector at the flap actuator corroded or loose
- PossiblePosition sensor in the flap actuator failed
- RareEngine controller input fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.