P0742: Torque Converter Clutch Circuit Stuck On
What to do
If the engine stalls each time you come to a stop and restarts immediately, that is this fault rather than an engine problem. Stalling at a junction is a real hazard — power steering and brake assistance go with it — so have it looked at promptly. Ask whether a brake switch code is also stored, since that is a cheap cause of the same symptom.
What this code means
The converter clutch is applied when it should have released. This is the failure that produces a genuinely disruptive symptom rather than a quiet one: with the clutch locked, the engine is mechanically tied to the wheels, so when the vehicle comes to a stop the stopping wheels take the engine with them and it stalls — exactly as a manual does if you brake to a halt without pressing the clutch.
That behaviour is unmistakable once recognised. The engine dies as you come to a junction, restarts immediately, runs perfectly, and does it again at the next one. Because the engine itself is faultless, the complaint is easily investigated as a stalling problem and the transmission never enters the conversation.
A related detail worth checking first: the transmission releases lock-up in response to the brake signal, so a brake switch reporting the brakes are never applied causes exactly this. That is a cheap fault producing an expensive-looking symptom, and it is stored as P0724 rather than here — so the two codes together point at the switch, not at the transmission.
Likely causes
Start here
- Faulty torque converter clutch solenoid · moderate
- Faulty brake light switch · easy
- Stuck valve in the valve body · specialist
Less common
- Debris in the transmission fluid · moderate
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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