P0906Gate Select Position Circuit A 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 gate select position signal on circuit A of an automated manual gearbox stays below its lowest valid value for longer than a calibrated time. Common causes are a short to ground on the signal line, a missing sensor supply, or an internal sensor defect; with many sensor designs a broken signal wire also reads low. No manufacturer documents this code publicly. Aisin AI and Isuzu describe select stroke and select position sensors with a defined voltage curve across the gates in their patents, so a value below that curve is clearly out of range; CARB calls for out-of-range checks on such inputs. P0907 is the matching high fault, P09A4 and P09A8 are the low faults of circuits B and C. Without a gate signal the gearbox usually locks gear changes or holds a safe gear.
- What you may notice
- Check engine or transmission warning light on
- No gear changes possible or gearbox stays in neutral
- Warning message about the transmission on the dashboard
- Likely causes
- LikelySignal wire chafed through and shorted to ground
- PossibleSensor reference supply interrupted or shorted
- PossibleInternal defect of the gate 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.