P07CB — Transmission Fluid Thermostat Performance
The transmission fluid thermostat (similar in function to a coolant thermostat — opens at a calibrated temperature to route ATF through the cooler) does not regulate temperature within the expected band. Either stuck open (ATF stays cold, friction modifier ineffective) or stuck closed (ATF overheats, oxidising the fluid).
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Transmission fluid thermostat
- Transmission cooler
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Thermostat stuck open
- Thermostat stuck closed
Possible 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
Diagnostic notes
- The malfunction indicator lamp may illuminate
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.