U04B2Invalid Data Received From Particulate Matter Sensor B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- U04B2 is the B counterpart of U04A4, intended for vehicles that carry a second smart PM sensor, for instance one per exhaust line or one ahead of and one behind a filter. Messages from sensor B still reach the engine controller, but their content is rejected. No manufacturer documents this code publicly; the public examples all use the single sensor A. By analogy with GM's handling of sensor A in 25OBDG04A, a receiver would count frames with a wrong rolling counter, protection value or checksum and set the code once too many fail within a short window. CARB 1968.2 demands that OBD detect PM sensor faults before the sensor can no longer serve filter monitoring. U01B1 means sensor B has gone silent. Expect a MIL and an incomplete filter check, with no change in drivability.
- What you may notice
- Check engine light on
- Particulate filter readiness not set
- Likely causes
- LikelyControl unit or element of PM sensor B damaged by heat, soot or moisture
- PossibleWiring or connector of sensor B chafed or corroded
- RareSensors A and B swapped or wrong variant fitted
- 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: €150 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.