P0744
PowertrainTorque Converter Clutch Circuit Intermittent
Old or dirty transmission fluid is behind most of these, usually on a box that's never had a fluid service. The torque converter has a lock-up clutch that bolts the engine straight to the gearbox at cruise to save fuel. The TCM watches that clutch engage and disengage, and when the signal cuts in and out instead of behaving, it logs P0744 for an intermittent fault in the clutch circuit. It's the intermittent nature that makes this one annoying, because the fault often won't be there when you go looking for it.
ⓘ Information only. This page provides general educational information about fault code P0744. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0744 mean?
P0744 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Torque Converter Clutch Circuit Intermittent.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, sometimes with a transmission temperature warning alongside it
- • Revs flaring up at a steady 60-70mph on the motorway as the lock-up clutch slips in and out
- • A shudder or judder through the car when the converter tries to lock up, often felt around 40-50mph
- • Harsh or confused gear changes that come and go
- • Worse fuel economy, most noticeable on longer motorway runs where the clutch should be locked
- • Box getting hot on a long run, occasionally enough to trigger limp mode
Possible causes
Causes commonly associated with P0744, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Old, low, or contaminated transmission fluid, the most common cause and the cheapest to rule out. Worn fluid clogs the valve body and stops the solenoid working cleanly
- 2. Faulty torque converter clutch solenoid, the part that actually controls lock-up engagement
- 3. Corroded or loose wiring and connectors in the TCC circuit, classic cause of an intermittent code because the connection breaks under heat or vibration
- 4. Internal transmission harness fault, the wiring loom inside the box itself degrades over time
- 5. Valve body or blocked fluid passages stopping the solenoid getting the pressure it needs
- 6. Mechanical wear inside the torque converter itself, the expensive end of the diagnosis
- 7. TCM playing up and sending bad commands, less common but it happens
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Pull freeze-frame data and check for any partner codes like P0741 or P0743, they tell you whether the box thinks the clutch is stuck or whether it's purely an electrical glitch
- 2. Check the transmission fluid level and condition. If it's dark, smells burnt, or has debris in it, deal with that before chasing anything electrical
- 3. Inspect the TCC wiring and connectors for corrosion, green crust, or bent pins. On an intermittent code this is where the fault usually hides
- 4. Measure the solenoid resistance with a multimeter, you're looking for roughly 2-4 ohms on most boxes. Way off that and the solenoid is suspect
- 5. Watch the TCC solenoid command against the actual feedback on a scan tool during a road test, that's the only reliable way to catch an intermittent fault in the act
- 6. Clear the code and drive it properly, including a sustained motorway cruise, to see whether it comes straight back
Common questions about P0744
How long should this take to put right? +
Depends entirely on what's causing it. A fluid and filter service is a couple of hours in a garage. Replacing an external solenoid or repairing a damaged connector is usually a half-day job. If it turns out to be an internal harness or the converter itself, you're looking at the gearbox coming out, which is a full day or more of labour and the bulk of the bill.
Is a cheap aftermarket solenoid worth fitting or should I stick with OEM? +
For the solenoid, a good quality aftermarket part from a known brand is fine and a lot of independents fit them every day. Steer clear of the cheapest no-name solenoids off eBay, because a marginal one will throw the same code back at you in a few hundred miles. If the torque converter itself needs doing, fit a proper remanufactured unit from a reputable supplier rather than the cheapest reman you can find, it's not a job you want to do twice.
Can I keep driving with this code? +
Short local trips won't hurt much. The thing to avoid is long motorway runs, because a clutch that's slipping in and out generates a lot of heat, and a hot box wears fast and can drop into limp mode. If it's juddering badly or the temperature light comes on, park it and get it looked at before you cook the converter.
Will this fail my MOT? +
There's no gearbox performance check in the MOT, so P0744 by itself won't fail you. The catch is the engine warning light. If the MIL is lit when the car goes on the ramp, that's an automatic fail under the current rules. Sort the underlying fault and clear the light before the test.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →