P0740 to P0744: torque converter clutch
The lock-up clutch in an automatic gearbox's torque converter has a circuit fault, does not engage, will not release or slips.
SeverityModerateUsually not urgent today, but it can get worse if left.
Can you keep driving?Drive gently, check it soonWhat does P0740 mean?
A torque converter couples the engine to an automatic gearbox through fluid, which always slips a little. At steady speeds a lock-up clutch inside it closes to join the two directly, saving fuel and heat. The gearbox computer commands it through a solenoid and checks the result by comparing engine speed with gearbox input speed. These codes say the command or the result is wrong.
What causes P0740?
- Low, old or burnt transmission fluid
- A failed lock-up solenoid or its wiring
- A worn lock-up clutch inside the converter
- A valve body fault that holds the fluid pressure wrong
What to check first for P0740
- Check the fluid level and smell it for burning, where the gearbox allows it
- Read the transmission module for other codes
- Watch the engine speed at a steady cruising speed: it should drop slightly when the clutch locks
- Note any shudder under light throttle at moderate road speeds
Can you drive with P0740?
Usually safe to drive gently to a workshop. Fuel use and gearbox temperature rise; avoid towing, long climbs and hard driving until it is repaired. A clutch stuck on can stall the engine when you stop, so keep the trip short in that case.
In states with an OBD-II emissions inspection, a car with the check engine light on fails the test until the fault is fixed.
Codes on this page
- P0740Torque Converter Clutch Circuit/Open
- P0741Torque Converter Clutch Circuit Performance or Stuck Off
- P0742Torque Converter Clutch Circuit Stuck On
- P0743Torque Converter Clutch Circuit Electrical
- P0744Torque Converter Clutch Circuit Intermittent
Related codes
Checked on · Rafael Soares
These are the generic meanings every manufacturer shares. Each brand adds its own detail, so your car's handbook, its service information and a qualified mechanic have the last word. OdoKeep has no connection with any manufacturer, and the app does not read codes from the car.
