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P0743 – Torque Converter Clutch Circuit Electrical (OBD2)

P0743 means "Torque Converter Clutch Circuit Electrical". The control unit has detected an electrical fault in the torque converter clutch circuit – an open, a short or a resistance outside the specification.

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P0743 quick summary

Fault codeP0743
MeaningTorque Converter Clutch Circuit Electrical
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityMedium
Can I drive?Usually yes, but if the converter stays locked (stuck on) the engine can stall when stopping – drive carefully and get it checked.
Repair cost€50 – €2,500

How the torque converter clutch works

The torque converter clutch (lock-up clutch) locks the torque converter at cruising speed to eliminate slip and save fuel; these codes cover its solenoid and performance.

A torque converter transmits power through fluid, which always involves some slip. To reduce it, a lock-up clutch inside the converter is engaged at steady speeds. A solenoid in the valve body controls it, and the control unit checks the slip between engine speed and turbine speed.

Codes P0740–P0744 report circuit faults, a clutch that does not lock (performance or stuck off), one that stays locked (stuck on, which can stall the engine when stopping) and intermittent faults.

Symptoms include higher fuel consumption, higher engine speed at cruise, shudder when the clutch engages and stalling when coming to a stop.

On VAG vehicles (VW, Audi, Škoda, Seat, Cupra), VCDS and older VAG testers can show this code as the five-digit VAG code 17127 (P0743). Both numbers mean the same fault.

Symptoms of P0743

  • Higher engine speed and fuel consumption at cruise
  • Shudder at around 60–80 km/h
  • Engine stalls when coming to a stop (stuck on)
  • Gearbox overheating
  • Check Engine or gearbox warning

Most common causes of P0743 (most likely first)

Mechanic's Pro Tip

Converter shudder is often fixed by fresh fluid of the exact specification – some gearboxes are very sensitive to friction modifiers in the oil. Try a fluid service before replacing the converter.

  1. 1.Faulty torque converter clutch (open or shorted winding)

    Most likely

  2. 2.Damaged wiring or internal gearbox harness

    Oil-soaked or chafed internal harnesses are common on automatic gearboxes.

  3. 3.Corroded or loose connector

  4. 4.Degraded or low gearbox fluid

  5. 5.Sticking valve in the valve body

  6. 6.Worn lock-up clutch in the torque converter

Step-by-step diagnostic guide

  1. 1

    Read codes and slip data

    Read the transmission codes and watch commanded lock-up and converter slip in live data at steady speed.

  2. 2

    Measure resistance at the connector

    Measure the torque converter clutch resistance at the control unit or gearbox connector and compare with the specification. Then check the wiring for shorts to ground.

    Multimeter: Shift and pressure solenoids typically read a few ohms up to about 15–30 Ω depending on design; "OL" means open, close to 0 Ω means shorted.

  3. 3

    Check fluid

    Check fluid level and condition.

  4. 4

    Test the solenoid

    Measure the solenoid resistance and command it with the scan tool.

    Multimeter: Many TCC solenoids read about 10–20 Ω (on/off type) or 3–6 Ω (PWM type) – check the specification.

  5. 5

    Check for shudder

    Drive at a steady speed and gently accelerate; shudder points to the clutch or fluid.

  6. 6

    Repair and adapt

    Replace the solenoid or fluid; if the converter clutch is worn, replace the torque converter, then run adaptations.

Frequently asked questions

Can I keep driving with P0743?

Usually yes, but if the converter stays locked (stuck on) the engine can stall when stopping – drive carefully and get it checked.

How much does it cost to fix P0743?

Typical repair costs are 50 € – 2500 €, depending on the cause and the vehicle. The most common fixes are: faulty torque converter clutch (open or shorted winding); damaged wiring or internal gearbox harness; corroded or loose connector. Always confirm the cause with the tests above before buying parts.

What does torque converter lock-up do?

It mechanically connects the engine to the gearbox at cruise, eliminating slip and saving fuel.

Why does my car stall when stopping?

If the lock-up clutch stays engaged, the engine is still connected to the wheels when the car stops.

What is the difference between P0743 and similar codes?

P0743 belongs to a group of codes for the same component that differ in the type or location of the fault: P0740 – Torque Converter Clutch Circuit Malfunction; P0741 – Torque Converter Clutch Circuit Performance or Stuck Off; P0742 – Torque Converter Clutch Circuit Stuck On; P0744 – Torque Converter Clutch Circuit Intermittent. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.