Transmission Fluid Temperature Sensor Circuit Low Input
The P0712 code indicates that the transmission control module (TCM) has detected a voltage signal from the transmission fluid temperature (TFT) sensor that is lower than the expected range (typically below 0.2 volts). This sensor is a thermistor that changes resistance with temperature; a low voltage reading suggests either a short to ground in the sensor circuit, a faulty sensor, or an internal TCM issue. The TCM uses this sensor to monitor transmission fluid temperature for shift scheduling and torque converter lockup. A low input can cause the TCM to default to a safe mode, potentially leading to harsh shifts or limp mode.
01. Most Common Causes
- Short to ground in the TFT sensor circuit
- Faulty transmission fluid temperature sensor
- Damaged wiring or connector at the transmission
- Internal TCM failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifts
- Transmission stuck in limp mode (e.g., 2nd gear only)
- Poor fuel economy
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check live data for TFT sensor voltage (should be 0.5-4.5V at operating temp).
Step 2: Visually inspect the TFT sensor wiring and connector for damage, corrosion, or shorts to ground.
Step 3: Disconnect the TFT sensor and measure resistance across its terminals; compare to manufacturer specs (e.g., 100k ohms cold, 1k ohms hot).
Step 4: Check for continuity between the sensor signal wire and ground; if continuity exists, repair the short.
Step 5: If sensor and wiring are good, test the TCM by checking voltage at the TCM connector; if low, replace TCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances. The transmission may enter limp mode, limiting speed and potentially causing internal damage due to improper shift patterns.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair if it's a simple wiring fix or sensor replacement. TCM replacement can cost $500-$1000.