Transmission

P0742 — Torque Converter Clutch Stuck On

Severity: medium Drive with care, to a shop

What P0742 means

The torque converter clutch (TCC) locks the engine to the automatic transmission at cruising speed to prevent slip. The control unit compares engine speed with transmission input speed and finds the clutch remains applied when it should be released. This ties the engine directly to the drivetrain at low speed and when stopping.

Symptoms

  • Engine stalls when braking to a stop
  • Shudder or vibration at low speed
  • Rough idle while in gear
  • Check Engine light on
  • Worse fuel economy in city driving

Possible causes

  1. Stuck TCC solenoid
  2. Valve body fault such as a sticking valve
  3. Torque converter clutch material welded or seized internally
  4. Damaged wiring or connector shorted to power or ground
  5. Dirty or degraded transmission fluid
  6. Rarely, a control module fault

How to diagnose

  1. Read all codes and freeze frame data and look for other transmission codes
  2. Check transmission fluid level and condition for color, smell and debris
  3. Inspect the TCC solenoid wiring and connector for damage and corrosion
  4. Measure solenoid resistance and compare to the service manual spec
  5. Command the TCC on and off with a scan tool and compare engine and input speeds
  6. Check line pressure per the manufacturer procedure
  7. If confirmed, drop the pan and inspect debris, then the valve body if needed

Common fixes

  • Change the transmission fluid and filter
  • Replace the TCC solenoid
  • Repair the wiring or connector
  • Clean or replace the valve body
  • Replace or rebuild the torque converter

Questions and answers

What does P0742 mean?

The control unit detected the torque converter clutch staying engaged when it should release. The usual culprits are the solenoid, valve body or the converter itself.

Can I drive with P0742?

Briefly and carefully, yes, but the engine may stall at stops, which is risky in traffic. The transmission can also wear, so repair it soon.

Will a fluid change fix P0742?

Sometimes, if dirty fluid is making a valve stick. If the fluid is fine, you usually need a new solenoid or valve body work.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.