How much does it cost to fix P0740?

DIY repair typically costs $15–$150 for parts. Professional repair runs $250–$1000 including parts and labor.

P0740

Powertrain

Moderate

Torque Converter Clutch Circuit Malfunction

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P0740 indicates a malfunction in the torque converter clutch (TCC) circuit. The torque converter clutch locks the engine to the transmission at highway speeds to improve fuel efficiency — similar to how a manual transmission is in direct drive. When the PCM commands the TCC to engage but detects an electrical issue in the circuit, this code is stored.

This code is often considered one of the more challenging transmission codes to diagnose because the problem could be the TCC solenoid (relatively inexpensive), the wiring, or the torque converter itself (very expensive). You'll most likely notice decreased fuel economy and possibly a shudder or vibration at steady highway speeds. Some vehicles may stall when coming to a stop if the converter locks up and doesn't release.

Start by checking the transmission fluid — dark, burnt fluid is a telltale sign of converter problems. If the fluid is clean, have the TCC solenoid and its wiring tested. A solenoid replacement is far less expensive than a torque converter replacement, so accurate diagnosis is crucial. P0740 is best diagnosed by a transmission specialist who can test the solenoid circuit, check hydraulic pressures, and determine whether the issue is electrical or mechanical.

Severity

Moderate — Address SoonThis Week

Symptoms

•Check Engine light illuminated
•Decreased fuel economy, especially on the highway
•Transmission may shudder or vibrate at highway speeds
•Engine may stall when coming to a stop
•Slight hesitation or surge during steady cruising

Likely Causes

Faulty TCC solenoid35%

The torque converter clutch solenoid controls lockup engagement. A failed or sticking solenoid is the most common cause of this circuit malfunction code.

Dirty or degraded transmission fluid25%

Contaminated ATF can clog or restrict the TCC solenoid, preventing it from operating correctly and triggering the circuit malfunction code.

Wiring or connector issue20%

Damaged, corroded, or loose wiring between the PCM and the TCC solenoid can cause an open or short circuit that triggers this code.

Failed torque converter12%

Internal damage to the torque converter itself can prevent proper lockup, though the code specifically points to a circuit issue rather than a mechanical failure.

PCM or TCM fault8%

In rare cases, the Powertrain or Transmission Control Module itself may have an internal fault that incorrectly triggers this code.