P0742: Torque Converter Clutch Stuck On (Meaning, Causes, Fixes)
What P0742 means
A torque converter couples the engine to an automatic transmission through fluid. To save fuel at steady speeds, the computer (the powertrain control module, PCM, or the transmission control module, TCM) energizes a torque converter clutch (TCC) solenoid that applies a clutch inside the converter, locking the engine and transmission together. The clutch has to release when you slow down or stop, or the engine gets dragged down. OBD-Codes.com says P0742 sets when the transmission control module detects a fault in the circuit that operates the TCC solenoid, and lists wiring shorted to power among the causes. RepairPal says the code means the PCM sees less than a 200 RPM difference between torque converter speed and transmission input shaft speed when the vehicle is slowing below 30 mph or the brake pedal is applied, which means the clutch is still locked when it should be released. RepairPal's short summary on the same page instead says the TCM sets it when the converter fails to lock, which contradicts its own detailed definition; the stuck-on description matches the code's name. It is a generic OBD-II code (1996 and newer) but repair steps vary by make and model. OBD-Codes.com notes it is similar to P0740, P0741, P0743, P0744, P2769 and P2770, and that if other transmission codes appear alongside P0742, an electrical failure is likely.
Severity: can I keep driving?
Stop and fix promptly
Get it diagnosed soon. RepairPal rates P0742 Urgent, meaning it can cause severe damage or be unsafe. OBD-Codes.com gives no severity rating, but warns that if the torque converter clutch really is stuck on, the engine may stall when you come to a stop, which is a common problem on certain GM models. A car that can die at stop signs or in traffic is a safety risk, so get it checked before relying on it.
Common symptoms
- Check engine light on (both sources)
- Engine stalls when coming to a stop, often after highway driving, and then usually restarts normally (OBD-Codes.com, common on certain GM models); dying when coming to a stop after freeway driving or misfire-like symptoms (RepairPal)
- Decrease in fuel economy (RepairPal)
- Vehicle will not shift out of the highest gear at freeway speed (RepairPal lists this)
Likely causes
Roughly most to least common, based on the sources below. Your vehicle may differ.
- Transmission wiring harness damaged, pinched or shorted to power (OBD-Codes.com)
- Failed torque converter clutch (lock-up) solenoid (both sources)
- Failed transmission control module (OBD-Codes.com)
- Defective torque converter clutch inside the converter (RepairPal)
- Defective valve body (RepairPal)
- Dirty transmission fluid restricting the hydraulic passages (RepairPal)
Diagnostic steps you can do
Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.
- Check the transmission fluid level and condition. RepairPal lists dirty fluid that restricts hydraulic passages as a cause.
- Read all stored codes and the freeze frame data. OBD-Codes.com says other transmission codes stored alongside P0742 make an electrical failure likely.
- Inspect the transmission wiring harness and connectors for damage, pinching or loose connections (OBD-Codes.com).
- Note when the problem happens. If the engine stalls when you stop after highway driving, tell the shop, because that points to the clutch actually staying applied (OBD-Codes.com, RepairPal).
Typical fixes
- Repair a damaged, pinched or shorted transmission harness (OBD-Codes.com)
- Replace the TCC solenoid if its resistance is out of the manufacturer's specification; on some models it is part of the internal harness and needs the oil pan removed (OBD-Codes.com)
- Service dirty transmission fluid (RepairPal)
- Repair the valve body or torque converter clutch if the clutch stays applied with the solenoid released (RepairPal)
- Replace or repair the TCM only after wiring and solenoid check out (OBD-Codes.com)
Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.
🛠 When to call a pro
- The engine stalls when you come to a stop
- Testing needs a factory wiring diagram, a multimeter, and an advanced scan tool to compare the TCC solenoid command with the actual feedback, plus a graphing meter or oscilloscope to check the duty cycle (OBD-Codes.com)
- Confirming a mechanically stuck clutch means watching converter slip speed and solenoid duty cycle on a test drive above 45 mph and slowing below 30 mph (RepairPal)
- RepairPal lists engine misfire, internal transmission and driveline problems as common misdiagnoses for this code
Where to buy
Plain search links. Always match parts to your exact year, make, model and engine.
FAQs
Is P0742 serious?
It can be. RepairPal rates it Urgent, and both sources say a converter clutch that stays applied can make the engine die when you stop. OBD-Codes.com gives no rating. Get it checked soon, especially if the engine has stalled.
Why does P0742 make my engine stall at stops?
The torque converter clutch locks the engine to the transmission. If it stays applied as the car stops, the stopped wheels drag the engine down, the same way a manual car stalls if you stop without pressing the clutch. OBD-Codes.com says the engine usually restarts and runs normally afterward.
What's the difference between P0742 and P0741?
P0742 is the torque converter clutch stuck on (not releasing). P0741 is the performance or stuck-off code, where the clutch doesn't lock up as it should. P0743 and P0744 cover electrical and intermittent faults in the same circuit.
How much does it cost to fix P0742?
Neither source gives a repair cost. It can range from a wiring repair or solenoid to a valve body or torque converter, so get a diagnosis or a written estimate before replacing parts.
Sources
Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.