What it means
The transmission control system detected that 10th gear could not be engaged. The code does not identify the cause.
At a glance
- Usually lights the check-engine light
How it works
The transmission control system monitors whether the requested gear is reached after a shift command. This code sets when 10th gear is requested but the system detects that it did not engage, without pinpointing the faulty component.
Common causes
Most likely first.
- Shift solenoid sticking or malfunctioning
- Low or degraded transmission fluid
- Hydraulic pressure or valve body fault
- Shift actuator or linkage fault
- Internal transmission wear or damage
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and scan for related transmission codes, noting the commanded gear, actual gear, and conditions when 10th failed to engage.
- Check fluid level and condition using the specified procedure, since low or degraded fluid can prevent the hydraulic pressure needed for the shift.
- Inspect wiring and connectors for the transmission’s shift controls, and check any accessible external actuator or linkage for damage or binding.
- Review live gear and input/output-speed data during a suitable test to confirm whether 10th is commanded and whether the transmission changes ratio.
- Test the relevant shift solenoid and actuator circuits according to the manufacturer’s diagnostic procedure.
- If electrical checks pass, check hydraulic pressure and valve-body operation, then investigate internal 10th-gear components if indicated.
Common fixes
- Correct a low fluid level or service degraded fluid as specified.
- Repair damaged wiring or connectors for the shift-control circuit.
- Repair a confirmed faulty or binding external actuator or linkage.
- Replace a shift solenoid confirmed to be sticking or faulty.
- Repair a verified hydraulic, valve-body, or internal transmission fault.
Can I keep driving?
Avoid relying on 10th gear for sustained highway driving if it will not engage, and do not use hard acceleration to compensate for the missing gear. If the transmission slips, loses drive, or shifts unpredictably, stop safely and arrange recovery.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.