Transmission Fluid Temperature Sensor Circuit Low
The Powertrain Control Module (PCM) or Transmission Control Module (TCM) detected that the voltage signal from the Transmission Fluid Temperature (TFT) sensor is lower than the manufacturer's specified range. This typically indicates a short to ground in the sensor circuit or a faulty sensor, causing the module to read an artificially high transmission fluid temperature.
While the vehicle can usually still be driven, a false high-temperature reading can cause the transmission to enter a limp mode, alter shift patterns, or prevent torque converter clutch engagement. It should be diagnosed soon to prevent potential drivability issues or masking actual transmission overheating.
Common symptoms
- Illuminated Check Engine Light
- Harsh or delayed transmission shifting
- Transmission stuck in a fail-safe or limp mode
- Torque converter clutch fails to engage
- Transmission temperature warning light illuminated on the dash
Likely causes
- Faulty Transmission Fluid Temperature (TFT) sensor
- Short to ground in the TFT sensor wiring harness
- Corroded, damaged, or loose electrical connector at the transmission
- Dirty or degraded transmission fluid
- Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Fluid that is extremely dark, smells burnt, or is significantly low, which could indicate severe transmission issues or cause erratic sensor behavior.
Visually inspect the TFT sensor wiring and connectors outside the transmission.
Look for: Chafed wires, melted insulation, or corroded pins that could cause a short to ground.
Use a scan tool to monitor live data for the Transmission Fluid Temperature.
Look for: A reading that is pegged at an impossibly high temperature even when the vehicle is cold, confirming a circuit low/short.
Disconnect the TFT sensor and check the reference voltage from the PCM/TCM.
Look for: A steady 5-volt reference signal at the connector; if missing, the wiring to the module or the module itself may be at fault.
Measure the resistance of the TFT sensor using a digital multimeter.
Look for: Resistance values that are out of the manufacturer's specified range for the current ambient temperature, indicating an internal short in the sensor.
This page explains the generic P0712 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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