P0740: Torque Converter Clutch Circuit

What does P0740 mean?

The torque-converter clutch control circuit is malfunctioning. The lockup clutch reduces slip during suitable cruising conditions; its circuit must work before lockup performance can be assessed reliably.

Generic OBD-II definition: Torque Converter Clutch Circuit. Confirm applicability in your vehicle service information.

Common causes

• Open or shorted TCC wiring
• Failed TCC solenoid
• Poor transmission connector or control fault

Symptoms

• Check engine light
• Higher cruising RPM or reduced economy
• Possible transmission behavior changes

Diagnostic focus

This is not automatically a failed torque converter. Restore the electrical circuit first; P0741 separately describes lockup performance or stuck-off behavior.

Can I keep driving with P0740?

Severity: Medium Avoid towing, steep loads, and prolonged driving until diagnosed. Stop and arrange recovery if the transmission slips, loses drive, overheats, or bangs into gear; driving through slip can cause further damage.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

• Inspect the transmission electrical connector
• Test the TCC solenoid and wiring to specification
• Verify commanded lockup and slip after repairing the circuit

Sources & review

• OBD-Codes.com: P0740
• TroubleCodes.net: generic code definitions

Definitions and diagnostic background checked 2026-11-06. Generic guidance, not a substitute for the service procedure for your exact year, engine, and transmission.