P280BTransmission Range Sensor B Circuit Not Learned
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P280B flags missing or invalid adaptation values for the second range sensor signal. Where a design reads A and B in different modules, as GM does with sensor A in the TCM and sensor B in the engine module, a replaced or reprogrammed engine controller can lose the B reference while A is still learned. No maker documents P280B publicly, and CARB 13 CCR 1968.2 gives only the general duty to monitor transmission inputs. GM's correlation check P2805 shows how closely both paths are compared afterwards: their duty cycles must add up to 100 % within about 5 %. Without a valid B reference the plausibility checks against A cannot run. Perform the learn with a scan tool once circuit codes P2800-P2804 are cleared.
- What you may notice
- Warning lamp after module replacement
- Gear position checks disabled, possible start refusal
- Likely causes
- LikelyModule reading sensor B replaced or reprogrammed without learn
- PossibleLearn procedure interrupted
- RareOpen circuit faults on sensor B preventing the learn
- 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: €50 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.