Fault codes › Powertrain › Generic (SAE standard) › Transmission › Transmission control

P0740 Torque converter clutch circuit

Needs attention Have it looked at soon. The car is usually driveable with care in the meantime.

What does P0740 mean?

P0740 is a generic powertrain code, defined by the SAE standard, so it means the same thing on every make and model: torque converter clutch circuit. It belongs to the transmission group of codes.

A control module stores the code when something it watches stays outside what it expects for long enough. On its own the code says which system complained, not which part has failed — the causes below, most likely first, are where to start.

Is it safe to drive with P0740?

Needs attention. Driveable, but heat kills gearboxes — get the fluid checked.

Common causes of P0740

Failed lock-up solenoid.
Low or old transmission fluid.
Worn torque converter.

Symptoms

Higher revs at motorway speed.
Shudder under light load.
Worse economy.

What to check first

Fluid condition.
Solenoid resistance.
Converter lock-up on a road test.

Can I just clear P0740?

You can, and the light goes out — but a fault that is still there sets the code again, often within a drive or two. Clearing also erases the freeze frame (what the engine was doing when the code was stored) and resets the emissions readiness monitors, so an MOT, smog or inspection test will wait until they have run again. Fix the cause first, then clear it, then watch whether it returns.

Read and clear P0740 from your iPhone with OBDTrip

Plug a Bluetooth OBD-II adapter into the car and OBDTrip reads every stored, pending and permanent code, explains each one in plain English like this, shows what the engine was doing when it was set, and clears the check engine light once the fault is fixed. It keeps a history of when each code comes back, and records every drive on its own from then on.

Needs a Bluetooth Low Energy adapter such as the Vgate iCar Pro — which adapters work with iPhone. Reading and clearing codes is part of an OBDTrip subscription.

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General guidance from OBDTrip's fault-code catalogue, not a diagnosis of your car. When a code points to brakes, steering, overheating or a flashing check engine light, have the car looked at before driving on.