P2743 Transmission Fluid Temperature Sensor "B" Circuit High

Definition

Common causes

• Faulty transmission fluid temperature sensor
• Wiring issues (short circuit or open circuit)
• Poor electrical connections
• Faulty transmission control module (TCM)
• Corroded connectors
• Damaged or frayed wiring harness
• High transmission fluid temperature
• Software issues in the TCM

Common misdiagnoses

• Faulty transmission fluid temperature sensor
• Wiring issues or short circuits in the sensor circuit
• Transmission control module (TCM) malfunction
• Low transmission fluid level or quality
• Faulty transmission solenoids
• Engine control module (ECM) issues
• Incorrectly diagnosed transmission problems
• Overheating transmission components

Troubleshooting steps

1. 1. Check for Additional Codes

   Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are multiple issues

2. 2. Inspect the Wiring and Connectors

   Visual Inspection: Check the wiring harness and connectors associated with the Transmission Fluid Temperature Sensor "B". Look for signs of damage, corrosion, or loose connections

3. 3. Connector Condition

   Ensure that the connectors are securely attached and free from dirt or moisture

4. 4. Test the Sensor

   Resistance Check: Use a multimeter to measure the resistance of the Transmission Fluid Temperature Sensor "B". Compare the readings to the specifications provided in the vehicle’s service manual

5. 5. Voltage Check

   With the ignition on (engine off), check the voltage at the sensor connector. It should match the expected voltage as per the manufacturer’s specifications

6. 6. Check for Short Circuits

   Inspect the wiring for any signs of short circuits to power or ground. A short can cause the circuit to read high

7. 7. Inspect the Transmission Fluid

   Fluid Condition: Check the condition of the transmission fluid. If it is burnt or contaminated, it may affect sensor readings

8. 8. Fluid Level

   Ensure that the transmission fluid is at the correct level, as low fluid can lead to incorrect temperature readings

9. 9. Test the Engine Control Module (ECM)

   If the sensor and wiring are functioning correctly, the issue may lie with the ECM. Check for any software updates or known issues with the ECM related to this code

10. 10. Clear the Code and Test Drive

    After performing the above checks and repairs, clear the trouble code using the OBD-II scanner. Take the vehicle for a test drive to see if the code returns

11. 11. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P2743 code for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes

12. 12. Professional Diagnosis

    If the problem persists after performing these steps, consider seeking help from a professional mechanic or transmission specialist who can perform more advanced diagnostics.Conclusion By following these troubleshooting steps, you can systematically identify and address the cause of the P2743 code. Always refer to the vehicle’s service manual for specific details and specifications related to your vehicle