P0740
Torque Converter Clutch Circuit Malfunction
A general fault has been detected in the torque converter clutch (TCC) lockup circuit. The TCC mechanically links the engine to the transmission input shaft above a certain speed to eliminate slip and improve fuel economy.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
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
Common causes
Ordered by how often each turns out to be the cause.
- TCC solenoid failedCommon
- Transmission fluid low or burntPossible
- Wiring fault to solenoidLess likely
Parts involved
- Torque Converter
- TCC Solenoid
- Transmission Fluid
P0740 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.