Transmission Fluid Temperature Sensor "B" Circuit High
The transmission fluid temperature sensor B circuit is reading a voltage that is too high, indicating the sensor may be faulty or there is a wiring issue. This prevents the transmission control module from accurately monitoring fluid temperature, which can affect shift timing and torque converter clutch operation.
What You Might Notice
- Check engine light illuminated
- Harsh or delayed transmission shifts
- Improper torque converter clutch operation
- Transmission may not shift smoothly between gears
- Possible transmission overheating due to incorrect cooling control
Most Common Causes
- 1
Faulty transmission fluid temperature sensor B
The temperature sensor itself has failed internally or developed an open circuit, causing it to send an artificially high voltage signal to the PCM.
- 2
Wiring or connector problems
Damaged wiring, corroded connectors, or a loose connection in the sensor B circuit can cause high resistance or incorrect voltage readings.
- 3
PCM or transmission control module fault
The powertrain control module or transmission control unit may have failed, causing it to misinterpret sensor signals or produce high voltage outputs.
- 4
Transmission internal problems
Internal transmission damage or fluid contamination may indirectly affect sensor operation or indicate a larger transmission issue requiring service.
How to Diagnose It
- 1
Check Faulty transmission fluid temperature sensor B — The temperature sensor itself has failed internally or developed an open circuit, causing it to send an artificially high voltage signal to the PCM.
- 2
Check Wiring or connector problems — Damaged wiring, corroded connectors, or a loose connection in the sensor B circuit can cause high resistance or incorrect voltage readings.
- 3
Check PCM or transmission control module fault — The powertrain control module or transmission control unit may have failed, causing it to misinterpret sensor signals or produce high voltage outputs.
- 4
Check Transmission internal problems — Internal transmission damage or fluid contamination may indirectly affect sensor operation or indicate a larger transmission issue requiring service.
How to Fix It
- 1
Replace transmission fluid temperature sensor B
Locate and remove the faulty sensor, then install a new OEM or quality aftermarket replacement sensor and reconnect the wiring harness.
- 2
Inspect and repair wiring and connectors
Check the sensor B circuit wiring for damage, corrosion, or loose connections. Repair or replace damaged wires and clean corroded connectors with dielectric grease.
- 3
Clear code and perform system test drive
After repairs, clear the trouble code using a diagnostic scanner and perform a test drive to verify the transmission shifts properly and the code does not return.
- 4
Replace PCM or transmission control module
If the sensor and wiring are confirmed good, the PCM or transmission control module may need replacement. This requires professional programming and should be done by a qualified technician.
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