P0740 Torque Converter Clutch Circuit Malfunction

P0740 points to a torque converter clutch circuit malfunction. The transmission controller detected a problem commanding or monitoring the converter clutch control path.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Transmission
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the torque converter from P0740 alone; circuit data, slip data, fluid condition, and companion codes must be evaluated.

Useful checks before replacing parts

Scan transmission data for TCC command, slip RPM, input speed, output speed, fluid temperature, and companion solenoid codes.
Check transmission fluid level and condition where serviceable, then inspect TCC solenoid wiring, connectors, fuses, and grounds.
Confirm whether the fault appears during converter lockup, cruise, warm operation, or immediately after startup.

Related OBD-II codes

These nearby transmission entries can help compare wording and fault area. They may share the same verification status as the source database.