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P0742 — Torque Converter Clutch Circuit Stuck

Generic OBD-II · all makesPowertrain (engine & transmission)

P0742 indicates that the torque converter clutch (TCC) circuit is stuck in the engaged position, meaning the PCM detects that the TCC is being commanded on but the clutch is not releasing as expected. This can cause the engine to lug at cruise speeds and may lead to overheating or reduced fuel economy.

Symptoms

What causes it — most likely first

1. Torque converter clutch solenoid stuck or failed

The TCC solenoid controls hydraulic pressure to engage/disengage the clutch. If it sticks open or fails electrically, the PCM sees the circuit as stuck.

2. Wiring or connector issues in the TCC circuit

Damaged, corroded, or loose wires/connectors between the PCM and TCC solenoid can create an open or short that mimics a stuck condition.

3. Valve body blockage or stuck valve affecting TCC pressure

Debris, wear, or a malfunctioning valve in the transmission valve body can prevent proper pressure modulation, keeping the clutch engaged.

4. Low, dirty, or incorrect transmission fluid

Insufficient fluid level or contaminated fluid reduces hydraulic pressure and can cause the TCC to remain engaged or behave erratically.

5. PCM/TCM failure (rare)

Only after verifying solenoid, wiring, fluid, and valve body are functional should the powertrain control module be considered; PCM issues are uncommon for this code.

How it's diagnosed

  1. Retrieve stored codes and freeze‑frame data; note any related transmission codes.
  2. Check transmission fluid level, condition, and temperature; top off or replace if needed.
  3. Visually inspect the TCC solenoid harness and connectors for damage, corrosion, or loose pins; repair as necessary.
  4. Measure TCC solenoid resistance with a multimeter (compare to spec) and command the solenoid via a scan tool to verify it clicks and changes resistance.
  5. If solenoid and wiring are OK, perform a hydraulic pressure test or valve‑body inspection to verify proper TCC pressure control.
  6. Only after all above checks pass, consider testing or replacing the PCM/TCM as a last resort.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0740 — Torque Converter Clutch CircuitopenP0741 — Torque Converter Clutch Circuit PerforP0743 — Torque Converter Clutch Circuit ElectrP0744 — Torque Converter Clutch Circuit IntermP0745 — Pressure Control SolenoidP0746 — Pressure Control Solenoid Performances

Frequently asked

Does P0742 mean I need to replace the PCM?

No. The PCM is rarely the cause; most often the fault lies in the TCC solenoid, its wiring, fluid condition, or valve‑body issues. Replacing the PCM without checking those components usually does not fix the code.

Can I continue driving with a P0742 code?

Driving is possible for short distances, but the stuck TCC can cause engine lugging, overheating, and reduced fuel economy. Prolonged driving may damage the transmission, so it's best to diagnose and repair promptly.

Will clearing the code fix the problem?

Clearing the code only turns off the check‑engine light; if the underlying fault remains, the code will return once the PCM detects the condition again.

How much does a typical TCC solenoid replacement cost?

Costs vary widely by vehicle make, model, and labor rates. Because we do not provide pricing or parts‑source advice, consult a qualified technician for an estimate specific to your vehicle.