P0923 code meaning
Gear Shift Forward Actuator Circuit High
Powertrain system Generic code P09xx codes Check engine light
What P0923 means
Set when the drive circuit of the forward shift actuator of an automated manual gearbox shows a voltage that is too high for the current switching state. Typical reasons are a valve or motor line shorted to battery voltage, or a driver stage in the module that no longer switches off; depending on circuit design an open load can also read high. No manufacturer documents this code publicly. A ZF patent describes double-acting shift cylinders whose chambers each have a 3/2 solenoid valve, and an Isuzu patent drives a shift motor forward or reverse by shift direction. CARB requires circuit checks on outputs. P0922 is the opposite low fault, P0920 the open circuit, P0927 the reverse direction. An actuator that stays energised can hold or force a gear, so shifting is usually locked.
P0923 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0923
- Transmission warning light on
- Gearbox locks in one gear or refuses to shift
- Possible grinding when a gear is pushed unintentionally
Common causes of P0923
- Most likelyDrive wire shorted to battery voltage
- PossibleDriver stage in the control module stuck on
- Less likelyOpen coil or winding read as high on some circuit designs
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Gear shift forward actuatorWiring harnessTCM
What each part of P0923 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. |
| 23 | The exact fault in that area. |
What to do next
- Note P0923 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 P0923
What does P0923 mean?
P0923 means "Gear Shift Forward Actuator Circuit High". Set when the drive circuit of the forward shift actuator of an automated manual gearbox shows a voltage that is too high for the current switching state. It is a generic code, so it means the same on every make.
Is it safe to drive with P0923?
Drive gently and only to a workshop. With P0923 the car can go into limp mode (reduced power) to protect itself.
Will P0923 fail an emissions test?
Yes, it can. P0923 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 P0923 to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P0923 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.