Transmission Fluid Temperature Sensor Circuit Low Input
The P0712 code indicates that the Powertrain Control Module (PCM) has detected a low voltage signal from the transmission fluid temperature (TFT) sensor circuit. This sensor is a thermistor that changes resistance based on fluid temperature; a low input typically means the sensor is reading an abnormally low voltage (high resistance), often due to a faulty sensor, wiring issues, or a short to ground. This can cause the transmission to operate in a failsafe mode, affecting shift quality and potentially leading to overheating.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting
- Transmission stuck in limp mode or failsafe mode
- Poor fuel economy
2. Most Common Causes
- Faulty transmission fluid temperature sensor
- Open or shorted wiring in the TFT sensor circuit
- Poor electrical connection at the sensor or PCM
- Low transmission fluid level or contaminated fluid
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the TFT sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Measure the TFT sensor resistance and compare to manufacturer specifications (typically 100k ohms cold, 100 ohms hot).
Step 4: Check for a short to ground or open circuit in the wiring between the sensor and PCM.
Step 5: If sensor and wiring are okay, test the PCM for proper operation (rare).
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the transmission may overheat or shift improperly, potentially causing internal damage. Limp mode may limit speed and gear selection.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY sensor replacement, or $150 to $300 at a shop including diagnosis and labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.