P0744
Torque Converter Clutch Circuit Intermittent.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 7
- AreaTransmission
- 44
- FaultThe specific fault in that area
What it means
P0744 is the generic code for an intermittent fault in the torque converter clutch (TCC) circuit. The transmission control unit has seen the TCC solenoid or its circuit work normally at times but drop out, or the commanded and actual lock-up state disagree, so the fault comes and goes. Exact detection criteria vary between manufacturers and gearbox types.
Symptoms
- Judder or shudder at steady cruising speeds, particularly when lock-up engages
- Engine revs flare or the engine speed rises without matching road speed
- Poorer fuel economy than usual, especially on motorway runs
- Gearbox warning light or malfunction indicator lamp on, sometimes only intermittently
- Stalling or hesitation when braking to a stop if the clutch sticks engaged
- Transmission running hotter than normal
Possible causes
- Damaged, chafed or corroded wiring or loose connector pins in the TCC solenoid circuit, including the connector at the gearboxlikely
- Failing TCC solenoid or lock-up control solenoid with intermittent internal resistance or shortlikely
- Low, degraded or contaminated transmission fluid causing erratic lock-up or solenoid operationpossible
- Internal valve body wear or sticking valve affecting the lock-up control, depending on the gearboxpossible
- Worn torque converter clutch lining or internal converter fault causing slip that the control unit flags as intermittentpossible
- Poor power or earth supply to the transmission control unit, or a low battery voltage eventpossible
- Fault within the transmission control unit itself or an outdated software calibration where the manufacturer has issued a correctionrare
How to diagnose
- Read all stored and pending codes and note the freeze frame data, such as road speed, load, gear and fluid temperature, to see when the fault occurs
- Check the transmission fluid level and condition against the manufacturer's procedure, looking for a burnt smell, dark colour or debris, noting that some gearboxes are sealed and need a specific check method
- Inspect the wiring loom and the gearbox connector for chafing, heat damage, corrosion, moisture and loose or pushed-back pins
- With the wiring flexed and the connector wiggled, watch live data for the TCC command, lock-up status and slip speed to see if the fault can be reproduced
- Measure the TCC solenoid resistance and compare it with the manufacturer's specification, and check the supply and control signals at the connector
- Check battery condition, charging voltage, and the power and earth connections to the transmission control unit
- Check for any applicable manufacturer bulletins or software updates for the specific model and gearbox
- If the electrical side is sound, carry out a road test with live data to assess converter slip and decide whether internal gearbox inspection is needed
How to fix
- Repair or replace damaged wiring and clean or replace faulty connectors or terminals
- Replace the TCC solenoid or the solenoid pack if it is out of specification or intermittent
- Correct the fluid level and renew degraded fluid and filter using the correct specification for the gearbox
- Repair or replace the valve body or worn internal components if they are the cause
- Replace or overhaul the torque converter if the clutch is slipping or damaged
- Restore good power and earth supplies, and apply a manufacturer-issued control unit software update only where an outdated calibration is a known cause
Can I keep driving?
Medium severity
The car can usually be driven for a short time, but fix it soon, because continued slipping or judder can overheat the fluid and damage the gearbox or converter. Avoid heavy loads, towing and long motorway runs until it is checked.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.