Powertrain, generic · Transmission

P086C Neutral Position Sensor A Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Neutral position sensor A is a three-wire Hall sensor on the shift shaft of a manual gearbox that reports neutral to the engine module; start-stop may only switch the engine off in neutral. Audi uses it as sender G701 on the Q3 and A3, GM on the 2019 Corvette ZR1 manual, where its faults suspend the gear ratio checks. Thresholds and MIL status are not published. P086C means the signal is below its lower limit: signal wire shorted to ground, supply missing or a sensor without output. GM lists it among the exclusions of its gear checks; the neutral state is then unknown and start-stop stays off.

Likely causes

Signal wire shorted to ground or supply wire open or chafed
Neutral position sensor faulty
Corrosion or water in the connector
5 V reference of the module disturbed

Symptoms

  • Start-stop not working
  • Start system warning in the cluster (Audi)
  • No noticeable change in driving

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–350
Time0.5–2 h

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

Parts involved

neutral position sensorsensor wiringengine control modulemanual transmission

Related codes

P086AP086BP086DP086EP086FP08AF

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