What it means
The transmission control module detects that gear selection is not performing as expected.
At a glance
- Usually lights the check-engine light
How it works
The transmission control module selects gears by commanding gear-select solenoids and monitoring transmission responses. It checks whether the gear selected by the control strategy matches the gear-selection behavior reported by the transmission. This code sets when gear-select performance is incorrect or inconsistent, which can cause delayed, harsh, or wrong gear changes.
Common causes
Most likely first.
- Fault in gear-select solenoid or related transmission component
- Wiring or connector fault
- TCM fault
Symptoms
- Transmission warning light
- Delayed, harsh, or incorrect gear selection
- Limited shifting or limp mode
How to diagnose it
- Record transmission codes and freeze-frame data, including the commanded gear and vehicle conditions when the fault occurred.
- Use a transmission-capable scan tool to compare commanded gear with reported gear and observe gear-select solenoid data during operation.
- Inspect gear-select solenoid connectors and the transmission harness for loose pins, corrosion, fluid intrusion, or damage.
- Test the identified gear-select solenoid and its wiring against the manufacturer's specifications, checking for open, shorted, or intermittent circuits.
- If the solenoid circuits pass, check related transmission components and module software or operation using the manufacturer's diagnostic procedure.
Common fixes
- Repair damaged or poorly connected wiring at the gear-select solenoid or transmission harness.
- Replace a failed gear-select solenoid identified by circuit and scan-data checks.
- Repair a related internal transmission component if testing confirms it is preventing the commanded gear selection.
- Update or replace the transmission control module only after the solenoid circuits and transmission components are verified.
Can I keep driving?
Drive only as needed and avoid high-speed trips, towing, and rapid acceleration while gear selection is incorrect or delayed. If the transmission slips, selects an unexpected gear, or enters limp mode, stop when safe 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.