P09A5Gate Select Position Circuit B High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Indicates that the gate select signal on circuit B has stayed above its highest valid value for longer than allowed. Typical reasons are a short of the signal wire to the sensor supply or battery voltage, an open sensor ground, or a defective sensor. No manufacturer publishes how it uses this code or what circuit B physically is. An Aisin AI patent shows the consequence of losing select feedback: warning, request to stop, then a limp-home in first gear. CARB requires out-of-range checks on such inputs. P09A4 is the low counterpart, P09A2 the general fault, P0907 and P09A9 the high faults of circuits A and C. A gearbox that can no longer confirm its gate restricts shifting.
- What you may notice
- Check engine or transmission warning light on
- Gearbox stays in one gear or in neutral
- Limp-home mode with very limited gear choice
- Likely causes
- LikelySignal wire of circuit B shorted to sensor supply or battery voltage
- PossibleOpen sensor ground or corroded ground pin
- PossibleInternal fault of the select sensor
- RareFaulty input stage in the transmission control module
- 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.