What it means
The transmission control system detected a performance problem during cold-start operation. The code does not identify a particular fluid, thermostat, or solenoid fault.
At a glance
- Usually lights the check-engine light
How it works
The transmission control system evaluates transmission performance during cold-start operation, when the fluid is cold and shifts may be affected by its flow and temperature control. This code sets when performance in that cold-start period falls outside the system’s expected behavior; it does not by itself identify whether the fluid or thermostat is at fault.
Common causes
Most likely first.
- Degraded ATF without cold-flow reserve
- Stuck transmission fluid thermostat
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
- Record freeze-frame data and note ambient temperature, transmission temperature, and shift behavior when the cold-start fault set.
- Check for related transmission codes and review cold-start live data to see whether transmission temperature readings are plausible and shift commands are being followed.
- Check fluid level and condition using the maker’s specified procedure, and verify that the fluid type and service history are appropriate for the vehicle.
- Inspect accessible transmission temperature sensor wiring and connectors for damage or poor contact.
- If the data supports a temperature-control issue, test the transmission fluid thermostat and its operation using the manufacturer’s procedure.
- If the thermostat and temperature readings are sound, investigate cold-fluid hydraulic performance and internal wear based on the recorded symptoms.
Common fixes
- Correct an improperly set fluid level using the specified procedure.
- Service degraded or incorrect transmission fluid with the specified fluid and method.
- Repair damaged temperature-sensor wiring or connectors if confirmed.
- Replace a transmission fluid thermostat confirmed to be stuck or malfunctioning.
- Repair other verified hydraulic or internal faults if cold-start performance remains abnormal.
Can I keep driving?
If the transmission shifts harshly or slips only when cold, drive gently until it warms and avoid towing or hard acceleration; persistent slipping can damage internal parts. Stop driving if it loses drive or cannot shift predictably.
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.