P0743: Torque Converter Clutch Circuit Electrical
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - expect higher rpm on the highway and worse fuel economy.
Symptoms
- Engine speed higher than normal at cruise
- Fuel economy down 2-4 mpg
- Shudder at light throttle in some cases
Likely causes, most common first
- Torque converter clutch solenoid winding failed
- Internal harness fault
- Case connector corroded
- Computer driver failure
Read P0743 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0743 is the electrical version of a torque converter clutch fault: the solenoid that locks the converter cannot be driven properly. Without lock-up the converter always slips a little, so the engine turns a few hundred rpm faster at every highway speed and the difference lands on the fuel bill.
The solenoid lives inside the transmission, but the diagnosis starts outside it: measure the solenoid's resistance at the case connector against specification. A correct reading moves suspicion to the external harness and the computer; an open or shorted reading means dropping the pan - at which point the fluid's condition is worth a look, since it grades the transmission's overall health while the pan is off anyway.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Cars that report P0743 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0743?
Yes - expect higher rpm on the highway and worse fuel economy.
How much does it cost to fix P0743?
Typical US repair costs range from $100 for the simplest fix (tcc solenoid) to $1,000 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0743. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.