Powertrain, generic (extended)

P280B Transmission Range Sensor B Circuit Not Learned

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Module reading sensor B replaced or reprogrammed without learn
Learn procedure interrupted
Open circuit faults on sensor B preventing the learn

Symptoms

  • Warning lamp after module replacement
  • Gear position checks disabled, possible start refusal

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–250
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

transmission range sensor btcm

Related codes

P280AP2800P2805P2806

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.