Transmission Fluid Pressure Sensor/Switch "B" Circuit High
The transmission fluid pressure sensor B circuit is reading higher than expected, indicating an electrical fault in the sensor or its wiring. This prevents the transmission control module from accurately monitoring fluid pressure, which may cause abnormal shift timing or transmission behavior.
What You Might Notice
- Check engine light illuminated
- Transmission shifting erratically or harshly
- Delayed gear engagement
- Reduced fuel economy
- Possible transmission entering safe mode (limited gear selection)
Most Common Causes
- 1
Short to power in signal circuit
The signal wire to the transmission fluid pressure sensor B is shorted to a positive voltage source, causing the sensor to report abnormally high pressure readings.
- 2
Failed transmission fluid pressure sensor
The TFPS sensor itself has failed internally or developed a short, preventing accurate pressure signal transmission to the TCM.
- 3
Open ground circuit
The ground wire connection to the transmission fluid pressure sensor B is broken or corroded, disrupting proper sensor signal return.
- 4
TCM programming issue
The transmission control module may require reprogramming or replacement if electrical circuits and sensor test good, though this is uncommon.
How to Diagnose It
- 1
Check Short to power in signal circuit — The signal wire to the transmission fluid pressure sensor B is shorted to a positive voltage source, causing the sensor to report abnormally high pressure readings.
- 2
Check Failed transmission fluid pressure sensor — The TFPS sensor itself has failed internally or developed a short, preventing accurate pressure signal transmission to the TCM.
- 3
Check Open ground circuit — The ground wire connection to the transmission fluid pressure sensor B is broken or corroded, disrupting proper sensor signal return.
- 4
Check TCM programming issue — The transmission control module may require reprogramming or replacement if electrical circuits and sensor test good, though this is uncommon.
How to Fix It
- 1
Inspect and repair wiring harness
Check the signal and ground wires to transmission fluid pressure sensor B for shorts to power, corrosion, or damaged insulation. Repair or replace damaged wiring as needed.
- 2
Replace transmission fluid pressure sensor B
Remove and test the TFPS sensor; if faulty, replace with a new OEM or quality equivalent sensor to restore accurate pressure monitoring.
- 3
Clean and secure electrical connectors
Disconnect and inspect the sensor connector for corrosion or poor contact. Clean with electrical contact cleaner and ensure connections are tight and secure.
- 4
Reprogram or replace transmission control module
If all wiring and sensors test properly, the TCM may require reprogramming or replacement. This should only be attempted after confirming all electrical components are functional.
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