P0744: Torque Converter Clutch Circuit Intermittent

What does P0744 mean?

The torque converter clutch (lock-up) connects pump and turbine mechanically; a solenoid – on/off, pulse-width modulated or proportional – moves a control valve in the valve body. Slip is engine speed minus turbine speed. Manufacturers do not use P0740–P0744 uniformly: Ford uses P0740 for open, P0742 for short to ground and P0744 for short to power, and reports stuck on as P2758. In J2012 P0744 is an intermittent fault in the converter clutch circuit, but no manufacturer document available to us uses it that way: Ford flags a short to power via the driver feedback line after 0.5–5 s with MIL, and Nissan's CVT bulletins treat it as a functional converter fault checked at the valve body and belt. GM does not use it. Short interruptions make the clutch drop out and reapply, and lock-up may be disabled for the trip.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light
• Lock-up missing or jerky at times
• Engine speed jumps when cruising

Common causes

• High Loose contact or corrosion at the transmission connector or harness
• Medium Ford: control wire shorted to positive
• Medium Solenoid with temperature-dependent winding fault
• Low Nissan CVT: converter or valve body mechanical

Likelihood is a general estimate across vehicles; your make and model may differ.