Powertrain, generic · Transmission

P091C Gear Shift Position Circuit B Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Set when the shift position signal on circuit B of an automated manual gearbox stays below its lowest valid value for longer than a calibrated time. Usually the signal line is shorted to ground, the sensor supply is missing, or the sensor has failed internally. No manufacturer documents this code publicly. Patents from Aisin AI and Nissan/Aichi present the shift stroke or shift position sensor as the feedback that confirms an engaged gear; with a reading below the valid band that confirmation is lost on this channel. CARB requires out-of-range checks on such inputs. P091D is the opposite high fault, P0916 and P095C are the low faults of circuits A and C, P091B the plausibility fault of circuit B. The gearbox may run in fallback mode.

Likely causes

Signal wire of circuit B shorted to ground
Open or shorted sensor supply line
Faulty shift position sensor B

Symptoms

  • Transmission or engine warning light on
  • Restricted gear changes or a held gear
  • Engine start may be blocked if neutral cannot be confirmed

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,500
Time0.5–4 h

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

Parts involved

gear shift position sensor bwiring harnesstcm

Related codes

P091AP091BP091DP0916P095C

References: law.cornell.edu, patents.google.com, patents.google.com.