Powertrain, generic · Transmission

P08B2 Neutral Position Sensor A/B Correlation

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

On a manual gearbox with two neutral sensors or two channels, the engine module compares A and B. P08B2 means they disagree: one reports neutral, the other a gear, or their values differ beyond a calibrated limit, while each may look fine electrically. No manufacturer documents P08B2 publicly. A GM patent describes exactly this layout: two Hall sensors with their own magnets on the shift shaft, whose PWM outputs must be identical in neutral as an integrity check. Audi's G701 and GM's LT5 Corvette use only the A codes. CARB 1968.2 (e)(15) requires rationality monitoring of inputs. Because neutral cannot be confirmed, start-stop and remote start stay off; usual fix is aligning or replacing the sensor.

Likely causes

One of the two neutral sensors drifting or faulty
Magnet on the shift shaft shifted or sensor misaligned after repair
Neutral position not relearned after component replacement

Symptoms

  • Start-stop unavailable
  • Start system warning in the cluster
  • Gear indicator may be blank or wrong

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–450
Time0.5–2.5 h

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

Parts involved

neutral position sensor aneutral position sensor bengine control module

Related codes

P086AP086BP08ADP08AEP08B3

References: law.cornell.edu, patents.google.com, static.nhtsa.gov.