Transmission · Powertrain · generic (SAE-defined)
P0743: Torque Converter Clutch Solenoid Circuit Electrical
P0743 means the transmission computer has detected an electrical fault, such as a short or abnormal voltage, in the circuit that operates the torque converter clutch solenoid.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0743 sets
The powertrain or transmission control module (PCM/TCM) drives the torque converter clutch (TCC) solenoid and monitors that circuit for faults. When it sees a voltage or current reading that indicates a short to ground, short to power, or other electrical problem, it sets P0743 and usually disables lockup. The fault thresholds are manufacturer-specific.
Common causes of P0743
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Shorted TCC solenoid coil
- Chafed wire shorting to ground or another circuit
- Fluid-soaked or corroded transmission connector
- Damaged internal transmission harness
- Faulty PCM/TCM solenoid driver
P0743 symptoms
- Check engine light on
- No torque converter lockup
- Higher cruising engine speed
- Reduced fuel economy
- Often no other drivability symptoms
How P0743 is diagnosed
- Scan all modules for codes and note freeze frame conditions.
- Inspect the external harness near the exhaust and transmission mounts for chafing or heat damage.
- Disconnect the transmission connector and inspect for fluid wicking or corrosion.
- Measure solenoid resistance and check for a short to the transmission case.
- Check circuit continuity and isolation from ground and power between the module and transmission.
- Use a bidirectional scan tool to command the solenoid and confirm response once wiring is verified.
Typical fixes for P0743
- Repair the chafed or shorted wiring
- Clean or replace the transmission connector
- Replace the TCC solenoid
- Replace the internal transmission harness
- Repair or replace the PCM/TCM if the driver has failed
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0743 FAQ
What does code P0743 mean?
P0743 means the transmission computer has detected an electrical fault, such as a short or abnormal voltage, in the circuit that operates the torque converter clutch solenoid. The standard definition is "Torque Converter Clutch Solenoid Circuit Electrical."
Can I drive with a P0743 code?
Generally yes in the short term, because the transmission normally keeps shifting. Expect lower fuel economy and possible extra heat, so schedule a diagnosis soon and avoid heavy loads.
How is P0743 different from P0740?
Both are electrical TCC solenoid codes. P0740 generally points to an open or general circuit fault, while P0743 typically flags an electrical problem such as a short, though exact definitions vary by manufacturer.
Can a bad solenoid damage the computer?
A shorted solenoid can overload the module's driver circuit, so it is wise to confirm solenoid resistance is correct before installing a replacement module.
Keep researching
More transmission codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.