U0652Lost Communication With EGR Sensor B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- U0652 covers a digital EGR sensor labelled B that has stopped delivering data. What B measures depends on the maker; it may be the position of a second valve or a pressure or temperature signal of the EGR path. No manufacturer documents U0652 publicly. GM's 2025 diesel table 25OBDG04B shows how loose the lettering is: it uses U0651 for the high-pressure valve and U0653 for the low-pressure valve, whose text even calls it the B position sensor, yet U0652 does not appear at all. Sections (e)(15.2.1)(B)(i) and (f)(15.2.1)(B)(i) of the CARB rule require a separate code when a digital input stops communicating. An analog sensor B reports P0486, P0407, P0408 and P046E. Whatever B serves, its EGR function and monitor are suspended until data returns.
- What you may notice
- MIL on
- EGR monitor incomplete
- Possibly reduced EGR operation
- Likely causes
- LikelyWiring to EGR sensor B open, shorted or heat-damaged
- PossibleConnector at sensor B corroded or loose
- PossibleSensor B electronics 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.