General transmission fault — TCM detected a problem and requested MIL. Read sub-codes with a full-system scanner for specifics.
Common symptoms
- Harsh or delayed shifts
- Slipping
- Transmission warning light
- Limp mode
Typical causes
- Low transmission fluid
- Failed shift solenoid
- Internal wear
- TCM communication fault
What scanner do you need?
Full-system scanner (engine, ABS, SRS, transmission, service resets)
Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.
Diagnostic tips
- Record freeze frame data when the code first sets
- Clear the code only after fixing the root cause
- Check for related pending codes that point to a common issue
- Verify battery voltage is above 12.4V before chasing sensor codes