The converter lock-up does not engage as commanded. The driver may notice higher rpm on the highway, higher consumption and sometimes transmission heat.
Likely causes, most common first
- Low or burnt transmission fluid
- Faulty lock-up solenoid
- Worn torque converter clutch
- Valve body fault
Parts usually involved
- Transmission fluid
- Lock-up solenoid
- Torque converter
- Valve body
Test before you replace
Check the fluid, command lock-up on a road test and compare engine and input speeds.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.