P091B code meaning
Gear Shift Position Circuit B Range/Performance
Powertrain system Generic code P09xx codes Check engine light
What P091B means
Plausibility fault of the shift position signal on circuit B in an automated manual gearbox. The voltage stays within its electrical limits, yet the value does not fit: it disagrees with circuit A, does not change while the shift actuator moves, or does not match the learned gear positions. No manufacturer documents this code publicly. A Nissan/Aichi patent notes that sensor mountings on shift parts can deform under vibration and falsify the reading, and an Aisin AI patent describes how the control continues when a stroke sensor is no longer trusted. CARB requires rationality checks on such inputs. P091A, P091C and P091D are the electrical faults of circuit B, P0915 the same check on circuit A. Gear changes may be limited.
P091B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P091B
- Transmission warning light on
- Harsh or aborted gear changes
- Fallback mode with fewer available gears
Common causes of P091B
- Most likelyWorn or drifting shift position sensor, channels A and B disagree
- PossibleBent sensor bracket or displaced magnet on the shift rail
- PossibleGear positions not relearned after actuator or module replacement
- Less likelyIncreased contact resistance in the sensor circuit
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Gear shift position sensor bWiring harnessTCM
What each part of P091B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9 | Area: transmission. |
| 1B | The exact fault in that area. |
What to do next
- Note P091B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P091B
What does P091B mean?
P091B means "Gear Shift Position Circuit B Range/Performance". Plausibility fault of the shift position signal on circuit B in an automated manual gearbox. It is a generic code, so it means the same on every make.
Is it safe to drive with P091B?
Drive gently and only to a workshop. With P091B the car can go into limp mode (reduced power) to protect itself.
Will P091B fail an emissions test?
Yes, it can. P091B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P091B to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P091B clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.