What does code P0740 mean?

P0740 — Torque Converter Clutch (TCC) circuit open. Lock-up clutch doesn't engage — engine revs high on highway, fuel economy suffers. Belongs to the powertrain.transmission system. Severity: warning.

What are the common causes of P0740?

Open TCC lock-up solenoid; Damaged wiring to the solenoid; Worn TCC lockup friction material — fluid full of wear debris; Clogged oil passage in the valve body; Worn planetary gear separator

Can I drive with code P0740?

Limited: reaching the nearest workshop is fine, but avoid long trips. May progress into a more serious fault.

How do I diagnose P0740?

Read the code and freeze-frame with a scanner, check related-system errors, inspect the components listed (wiring, connectors, sensors). See the "How to diagnose" section above for the full step-by-step.

How do I clear code P0740?

The code can be cleared via an OBD-II scanner (e.g. ELM327 + the Car Diagnostics app): plug the adapter into the OBD port, go to Errors → Clear. If the underlying cause isn't fixed, the code will return within a few drive cycles.

OBD-II Code P0740 — Car Diagnostics Platform

What it means

Common causes

Open TCC lock-up solenoid
Damaged wiring to the solenoid
Worn TCC lockup friction material — fluid full of wear debris
Clogged oil passage in the valve body
Worn planetary gear separator
Sometimes just fluid change needed — old fluid loses pressure hold

How to diagnose

01
Read all stored and pending codes with an OBD-II adapter — get the full picture, not just the one code.
02
Capture freeze-frame data (RPM, coolant temperature, engine load) at the exact moment the code triggered.
03
Inspect the named subsystem with our app's AI explanation — get vehicle-specific causes for your make, model and year.

Decode P0740 on your actual car

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