The P0743 code in your 2022 Nissan Altima indicates the torque converter clutch circuit is stuck in the disengaged (off) position. While the Altima uses a CVT (Continuously Variable Transmission), it still employs a torque converter with a lockup clutch for efficiency at highway speeds.
CVT Torque Converter Operation
Nissan's Xtronic CVT uses a torque converter for initial vehicle launch, then locks up for direct drive efficiency. The TCC lockup clutch reduces slip and heat at steady cruising speeds. When the circuit is stuck off, the converter never locks, reducing fuel economy and increasing transmission operating temperature.
Common Causes
- Open circuit in TCC solenoid wiring
- Failed TCC solenoid (stuck open)
- Corroded electrical connector
- TCM/ECM output driver failure
- Internal valve body stuck in unlock position
- Damaged torque converter lockup clutch
Symptoms You'll Experience
- Noticeably reduced fuel economy
- Higher than normal engine RPM at highway speeds
- Transmission running warmer than normal
- Check engine light on
- Possible CVT whine at sustained speeds
- Sluggish acceleration feel
Nissan CVT Fluid Importance
The 2022 Altima requires Nissan NS-3 CVT fluid exclusively. Using incorrect fluid can damage the CVT and affect TCC operation. Always verify proper fluid type during diagnosis.