Transmission Fluid Temperature Sensor Circuit Low Input
What does this mean?
Code P0712 indicates a problem with the transmission fluid temperature sensor.
Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Subaru Wrx models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.
Common Causes
Low, dirty, or burnt transmission fluid
Damaged, chafed, or broken wiring harness
Corroded or loose electrical connector
Symptoms to Watch For
- Check Engine Light is illuminated
- Transmission overheating warning
- Hard or harsh gear shifting
How to Diagnose
Common Solutions
Replace the Transmission Fluid Temperature (TFT) Sensor: This is the most frequent solution if the sensor itself is faulty, exhibiting incorrect resistance readings or causing the 'low input' signal. The sensor may be a standalone component, or it might be integrated into the transmission's internal wiring harness (lead frame) or even the valve body assembly, requiring a more involved replacement procedure.
Repair or Replace Damaged Wiring Harness: If the diagnostic steps reveal a short to ground, an open circuit, or excessive resistance in the wiring leading to the TFT sensor, the damaged section of the harness must be meticulously repaired or replaced. Ensure all connections are clean, tight, and free of corrosion to prevent future issues.
Replace the Transmission Lead Frame or Valve Body: On many modern transmissions, the TFT sensor is an integral part of the internal wiring harness (often called a lead frame) or the entire valve body assembly. If the sensor is not separately replaceable, the entire lead frame or valve body may need to be replaced to resolve the P0712 code. This is a more complex and costly repair due to the component integration.