P091CGear Shift Position Circuit B Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Transmission or engine warning light on
- Restricted gear changes or a held gear
- Engine start may be blocked if neutral cannot be confirmed
- Likely causes
- LikelySignal wire of circuit B shorted to ground
- PossibleOpen or shorted sensor supply line
- PossibleFaulty shift position sensor B
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.