Transmission Fluid Temperature Sensor "B" Circuit
Code P2740 indicates a malfunction in the Transmission Fluid Temperature Sensor B circuit, which measures transmission fluid temperature to optimize shift timing and torque converter operation. When this sensor fails or its circuit is compromised, the transmission control module cannot properly regulate transmission behavior, leading to harsh shifts and potential transmission damage if left unaddressed.
What You Might Notice
- Check engine light illuminated
- Harsh or delayed transmission shifts
- Improper torque converter clutch operation
- Transmission slipping or overheating
- Reduced fuel economy
Most Common Causes
- 1
Faulty transmission fluid temperature sensor
The temperature sensor itself has failed or become contaminated, preventing accurate fluid temperature readings to the transmission control module.
- 2
Wiring or connector problems
Corroded, damaged, or loose wiring connections in the sensor circuit prevent proper signal transmission from the sensor to the PCM.
- 3
Transmission internal issues
Internal transmission problems may cause erratic sensor readings or prevent the sensor from functioning correctly in its mounting location.
- 4
Faulty PCM or TCM
A defective powertrain or transmission control module may fail to properly read the sensor signal or process temperature data.
How to Diagnose It
- 1
Check Faulty transmission fluid temperature sensor — The temperature sensor itself has failed or become contaminated, preventing accurate fluid temperature readings to the transmission control module.
- 2
Check Wiring or connector problems — Corroded, damaged, or loose wiring connections in the sensor circuit prevent proper signal transmission from the sensor to the PCM.
- 3
Check Transmission internal issues — Internal transmission problems may cause erratic sensor readings or prevent the sensor from functioning correctly in its mounting location.
- 4
Check Faulty PCM or TCM — A defective powertrain or transmission control module may fail to properly read the sensor signal or process temperature data.
How to Fix It
- 1
Replace transmission fluid temperature sensor
Remove the faulty sensor from the transmission pan or housing and install a new OEM or quality replacement sensor, then clear the code and test drive.
- 2
Inspect and repair wiring harness
Check the sensor wiring connector and circuit for corrosion, damage, or loose connections. Clean corroded terminals or replace damaged wiring as needed.
- 3
Check transmission fluid level and condition
Verify transmission fluid is at proper level and not contaminated or burnt. Low or degraded fluid can affect sensor operation and transmission performance.
- 4
Test or replace PCM/TCM
If sensor and wiring are confirmed good, have the transmission control module tested or reflashed by a qualified technician; replacement may be necessary if module is defective.
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