Fault code P0744 – a step-by-step guide to diagnosing and fixing it

Error code P0744 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system detects a fault in the torque converter clutch circuit of the automatic transmission control unit. This DTC P0744 indicates a problem with the torque converter lock-up clutch, which is responsible for the mechanical connection between the engine and transmission. This fault code may have slightly different names for different manufacturers, but always refers to the same automatic transmission system.

What causes can this fault code have?

• Defective lock-up clutch in the torque converter
• Contaminated or used transmission oil
• Clogged transmission oil filter
• Defective solenoid valve for the clutch control
• Damaged wiring to the torque converter
• Faulty transmission control unit (TCM)
• Mechanical damage to the torque converter
• Loose or corroded plug connections
• Defective speed sensor on the transmission

What symptoms occur in parallel with fault code P0744?

• Shifting problems: The automatic transmission shifts jerkily or irregularly between gears
• Increased fuel consumption: The engine works less efficiently due to a lack of lock-up
• Overheating: The transmission becomes unusually hot while driving
• Power loss: Noticeable reduction in engine power, especially at higher speeds
• Vibrations: Unusual vibrations in the vehicle while driving
• Starting problems: Delayed starting or jerky behavior when accelerating

How can the problem with error code P0744 be resolved?

• Repairing this trouble code requires systematic diagnosis and targeted measures to restore proper function.
• Change the transmission oil and filter: Completely replace the automatic transmission oil to the manufacturer's specification and replace the transmission oil filter to remove contamination
• Check and replace solenoid valve: Removal and function test of the control valve for the lock-up clutch, complete replacement of the valve block if defective
• Repair wiring and plug connections: Visually inspect all electrical connections to the torque converter, clean corroded contacts and replace damaged cables
• Replace torque converter: If the lock-up clutch is mechanically defective, complete replacement of the torque converter including professional refilling
• Diagnose transmission control unit: Software test of the TCM with manufacturer diagnosis, update or replace the control unit if necessary
• Check speed sensors: Function test of all transmission-relevant sensors and replacement of defective components for correct signal transmission