U0653Lost Communication With EGR Sensor C
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- On GM's 2025 diesel with high- and low-pressure EGR (table 25OBDG04B), EGR sensor C is the SENT position sensor of the low-pressure valve, which as usual for such loops takes exhaust after the particulate filter and feeds it ahead of the compressor. Oddly, the table's text calls this valve the B position sensor while filing its codes under C. U0653 is stored when 480 of 600 checks every 6.25 ms see outdated data while the protocol sits permanently low or high, a corrupt message, or counters that froze; GM rates this Type A, lighting the MIL on the first trip. A raw level below 1 % on the same sensor is P044C, and P044A to P044E cover the analog faults of sensor C. While the low-pressure valve position is unknown, its loop is shut and the high-pressure loop has to cover alone.
- What you may notice
- MIL on from the first trip
- Low-pressure EGR disabled, higher NOx
- EGR monitor not ready
- Likely causes
- LikelyWiring to the low-pressure EGR valve damaged near the exhaust
- PossibleConnector corroded by road splash
- PossiblePosition sensor in the low-pressure EGR valve 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 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.