Torque Converter Clutch Circuit Performance or Stuck Off
Your torque converter clutch isn't engaging or disengaging properly, like a manual transmission's clutch pedal getting stuck. The transmission can't efficiently lock the engine to the wheels when it should, wasting fuel and causing performance issues.
The ECM monitors torque converter clutch solenoid current, oil pressure, and engine-to-transmission speed ratios. It expects the clutch to lock when speeds match within a threshold range for fuel efficiency. If actual slip remains above expected values after solenoid engagement, the fault is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Torque Converter Slip Speed | 0-200 RPM when locked | >200 RPM sustained at highway speed |
| Solenoid Control Current | 0.5-2.0 amps | No response or out-of-range current draw |
Code P0742 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0742 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.