P0921Gear Shift Forward Actuator Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Plausibility fault in the drive circuit of the forward shift actuator of an automated manual gearbox. The circuit is neither open nor shorted, but current, voltage or the resulting movement do not fit the command, for example a current that is too high for the requested stroke or a shift position that hardly changes. No manufacturer documents this code publicly. A Hyundai/Kia patent explains that jamming raises the motor load of a shift actuator and must be caught early, and a ZF patent shows double-acting shift cylinders with one solenoid valve per chamber. CARB requires functional checks on such outputs. P0920, P0922 and P0923 are the clear electrical faults, P0925 the reverse direction, P0919 the missed target. Forward shifts become slow or fail.
- What you may notice
- Transmission warning light on
- Slow, harsh or aborted gear changes in one direction
- Fallback mode with fewer available gears
- Likely causes
- LikelySticking shift valve, worn shift motor or stiff shift linkage
- PossibleSolenoid or motor resistance out of specification
- PossibleIncreased contact resistance in connector or wiring
- RareInsufficient hydraulic pressure on hydraulic units
- 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: €150 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.