Transmission

P0740 — Torque Converter Clutch Circuit Malfunction

Severity: medium Drive with care, to a shop

What P0740 means

P0740 means the transmission control unit (TCM or PCM) detected a fault in the electrical circuit that controls the torque converter clutch. Normally, at cruising speed a solenoid applies fluid pressure to lock the converter and remove slip between the engine and transmission. If the commanded state isn't achieved or the circuit is open or shorted, the clutch can't lock or release properly.

Symptoms

  • Check Engine Light is on
  • Harsh or erratic shifting
  • Shudder or vibration at low speed
  • Worse fuel economy, especially on the highway
  • Transmission overheating
  • Engine stalling when the clutch sticks applied

Possible causes

  1. Failed torque converter clutch solenoid
  2. Damaged wiring or corroded connectors in the transmission harness
  3. Low or contaminated transmission fluid
  4. Faulty TCM or PCM
  5. Clogged valve body or worn valves
  6. Internal torque converter or transmission mechanical failure

How to diagnose

  1. Scan all codes and freeze-frame data and look for other transmission codes
  2. Check transmission fluid level and condition: color, smell, debris
  3. Inspect the transmission harness and connector for damage, fluid intrusion, and corrosion
  4. Measure the solenoid resistance and compare it with the factory spec
  5. Check power and ground and test the wiring to the control unit for opens and shorts
  6. Command the solenoid with a scan tool and watch the response and RPM
  7. Drop the pan and look for metal debris and valve body condition
  8. Check for control unit software updates

Common fixes

  • Replace the torque converter clutch solenoid
  • Repair wiring or replace damaged connectors
  • Change the transmission fluid and filter
  • Reflash or replace the control module
  • Repair or replace the torque converter or valve body

P0740 on different brands

Ford · manuals
On Ford, the extended code P0740:11 means a circuit short to ground, which describes the detected circuit condition rather than a confirmed failed part.

Questions and answers

Can I drive with a P0740 code?

For a short time, if shifting isn't severe and nothing is overheating. But a slipping or stuck clutch can damage the transmission, so get it diagnosed soon.

What most often causes P0740?

A failed TCC solenoid or damaged wiring in the transmission harness is the most common cause. Also check the fluid level and condition.

Will changing the transmission fluid fix P0740?

If the cause is low or dirty fluid, it might. If the solenoid or wiring is at fault, a fluid change alone won't clear it.

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.