P0743: Torque Converter Clutch Circuit Electrical
The transmission control unit has detected an electrical fault in the torque converter clutch solenoid circuit.
Normal risk
Usually drivable. Fuel use and transmission temperature may rise. Have it checked soon.
Short answer · Can I keep driving with P0743?
Usually yes. The converter clutch may not lock, or may lock and release unexpectedly, so engine speed can change at steady cruising. Have it checked soon.
What does P0743 mean?
P0743 means the current or voltage in the torque converter clutch solenoid circuit is not plausible, for example because of a short, an open circuit or a failed solenoid. A damaged internal harness, a corroded connector or a fault in the control unit output are other typical causes.
What the car does when the code is set
The check engine light comes on. Depending on the transmission fault, shifting may be normal, harsh or delayed, or the transmission may stay in one gear (limp mode).
How the system works
An automatic transmission has its own control unit that reads speed sensors, the selector position and pressure sensors, and controls shifting through solenoids. When it detects a fault that can affect emissions, it asks the engine control unit to light the check engine lamp. Because the engine control unit stores a code for that request, a basic scanner often shows only this code, while the detailed code stays in the transmission control unit.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Fault in the transmission control systemThis code only reports that the transmission control unit has stored its own fault.
- Low or old transmission fluidOften found together with shifting codes.
- Sensor or solenoid faultSpeed sensors, pressure solenoids and wiring.
- Communication problemBetween the engine and transmission control units.
How it is diagnosed
- Read the transmission control unitUse a scan tool that reads the transmission module: the real cause is stored there.
- Check the fluidCheck level and condition as the service data describes.
- Follow the specific codeDiagnose the code from the transmission module.
- Clear and test-driveClear codes from both modules and test-drive.
Questions about P0743
How does P0743 differ from P0740?
P0740 is the general circuit fault. P0743 narrows it down to an electrical fault in the solenoid circuit, which helps the workshop look in the right place.
Why does my basic scanner only show this code?
Many simple scanners read only the engine control unit. A scanner that reads the transmission module shows the real fault code.
Is P0700 a transmission failure?
Not necessarily. It only reports that the transmission control unit stored a fault. The real code there shows what is wrong.