Code P0740 on the 2024 Honda Pilot indicates a malfunction in the torque converter clutch (TCC) circuit. This code typically means the TCC solenoid or its circuit has an issue preventing the torque converter lockup clutch from engaging when commanded.
Torque Converter Clutch Purpose
The torque converter allows the engine to idle without stalling while in gear by using fluid coupling. However, this coupling causes some efficiency loss. The lockup clutch mechanically connects the engine to the transmission at cruise speeds, eliminating slip and improving fuel economy by 2-5%.
TCC Stuck Off Effects
When the TCC cannot engage, fuel economy decreases noticeably during highway driving. Transmission fluid may run hotter due to continuous converter slip. You might notice the engine RPM stays slightly higher than normal at steady cruise speeds where lockup should occur.
Diagnostic Direction
P0740 can indicate TCC solenoid failure, wiring issues to the solenoid, or internal transmission problems preventing clutch engagement. On Honda transmissions, solenoid issues are common. Check the solenoid resistance and verify the TCM can command it properly.
Repair Considerations
The TCC solenoid is often accessible without major transmission disassembly. On a 2024 model, warranty coverage should apply. If the solenoid tests good, internal torque converter damage may require converter replacement.