Powertrain, generic · Transmission

P091A Gear Shift Position Circuit B

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Circuit B is a second channel reporting the shift position of an automated manual gearbox, for instance a redundant sensor track or a separate sensor on another shift rail. This general circuit code sets on an electrical fault on that signal that matches none of the more specific B variants. No manufacturer documents the code publicly, and which physical sensor carries the letter B depends on the design. Patents from Aisin AI and Nissan/Aichi describe shift stroke sensors as the feedback for gear engagement, an Aisin AI patent also covers the fallback when a stroke sensor fails. CARB requires circuit checks on such inputs. P091B to P091D are the B siblings, P0914 and P095A the same signal on circuits A and C. Shifting may be restricted.

Likely causes

Loose or corroded connector at the shift position sensor
Damaged signal, supply or ground wire of sensor circuit B
Faulty shift position sensor B
Faulty sensor input in the transmission control module

Symptoms

  • Transmission or engine warning light on
  • Slower or restricted gear changes in fallback mode
  • Gearbox may hold a gear or stay in neutral

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
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

P0914P091BP091CP091DP095A

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