The torque converter clutch (lock-up) connects pump and turbine mechanically; a solenoid – on/off, pulse-width modulated or proportional – moves a control valve in the valve body. Slip is engine speed minus turbine speed. Manufacturers do not use P0740–P0744 uniformly: Ford uses P0740 for open, P0742 for short to ground and P0744 for short to power, and reports stuck on as P2758. P0740 concerns the control circuit of the converter clutch solenoid. Ford flags an open circuit when the driver feedback line disagrees with the command for 0.5–5 s, with MIL; a 2006 GM table checks 0/12 V with more than 43 of 50 failed counts after two trips – newer GM units use P2761/P2763/P2764. FCA's Ram 6.7 reads P0740 as converter slip out of range and moved it to two trips by software in 2013. The clutch is then switched off: higher engine speed when cruising, more fuel, hotter fluid.
Medium severity. Can I keep driving?You can use the car in moderation to reach a repair shop, but avoid long highway drives, steep grades, and towing because the transmission fluid runs hotter. If the engine stalls when you stop, the torque converter clutch may be locking up and it is best not to drive.
Symptoms
- Check engine light or transmission warning
- No lock-up: engine speed about 100–300 rpm higher when cruising
- Higher fuel consumption, hotter transmission fluid
Most likely causes
- Open or corroded harness or transmission pass-through connector
- Converter clutch solenoid coil open
- Internal transmission harness or mechatronic unit
- Driver stage in the module faulty
- FCA: actual converter slip (clutch wear, fluid) or software
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P0740 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 7: Transmission
- 40: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0740?
You can use the car in moderation to reach a repair shop, but avoid long highway drives, steep grades, and towing because the transmission fluid runs hotter. If the engine stalls when you stop, the torque converter clutch may be locking up and it is best not to drive.
What causes code P0740?
The most common causes are: open or corroded harness or transmission pass-through connector; converter clutch solenoid coil open; internal transmission harness or mechatronic unit.
Related codes
- P0741Torque Converter Clutch Circuit Performance/Stuck Off
- P0742Torque Converter Clutch Circuit Stuck On
- P0743Torque Converter Clutch Circuit Electrical
- P0744Torque Converter Clutch Circuit Intermittent
- P2763Torque Converter Clutch Pressure Control Solenoid Control Circuit High
- P2764Torque Converter Clutch Pressure Control Solenoid Control Circuit Low
Sources
- newtonnet.co.uk: fordobd2012
- fordservicecontent.com: obd summary diesel 2023
- gsi.ext.gm.com: 2006trans11
- static.nhtsa.gov: MC 10221090 9999
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.