P0712
UniversalTransmission Fluid Temperature Sensor Circuit Low Input
Medium SeverityThis code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) is receiving an abnormally low voltage signal from the Transmission Fluid Temperature Sensor (TFTS) circuit. This typically suggests the sensor is reporting very cold fluid temperatures or an open circuit, which can lead to incorrect transmission shift points, potential damage due to overheating, and reduced fuel efficiency.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is safely supported on a level surface before working underneath. Allow the transmission fluid to cool down before attempting any work involving the transmission, as it can be extremely hot. Disconnect the battery before performing any electrical work. Wear appropriate personal protective equipment, including gloves and eye protection.
Common Symptoms
- Check Engine Light illuminated
- Harsh or erratic transmission shifts
- Transmission staying in a lower gear longer than usual
- Poor fuel economy
- Transmission may not shift into overdrive
- Transmission overheating warning (less common but possible)
Common Causes
- Faulty Transmission Fluid Temperature Sensor (TFTS)
- Open or short circuit in the TFTS wiring harness
- Corroded or damaged TFTS electrical connectors
- Low transmission fluid level (though less common for a 'low input' code)
- Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM) (rare)
Frequently reported on: General/Universal
Diagnostic Steps
- Connect an OBD-II scanner to confirm the P0712 code and check for any other related codes.
- Visually inspect the wiring harness and connectors leading to the Transmission Fluid Temperature Sensor for any signs of damage, corrosion, or loose connections.
- If accessible, test the resistance of the TFTS using a multimeter (compare readings to service manual specifications, often varies with temperature). A very low resistance or infinite resistance can indicate a fault.
- Check the transmission fluid level and condition. While not a direct cause of a 'low input' signal, ensuring proper fluid health is always good practice.
- If testing indicates a faulty sensor or if visual inspection reveals severe wiring damage, replace the Transmission Fluid Temperature Sensor and/or repair the wiring.
- Clear the fault codes from the PCM/TCM and perform a test drive to see if the code returns and if symptoms have resolved.
👨🔧 When to Call a Professional
While inspecting the wiring and basic sensor tests can be a DIY task, if diagnosis points to the sensor being inside the transmission pan, or if you suspect more complex electrical issues, it's best to consult a professional transmission specialist. Improper transmission work can lead to costly damage.
Commonly Asked Questions
Can I drive my car with a P0712 code?
Driving with a P0712 code is not recommended for an extended period. Incorrect temperature readings can cause the transmission to shift improperly, potentially leading to increased wear, overheating, and significant transmission damage over time.
Where is the Transmission Fluid Temperature Sensor located?
The sensor's location varies by vehicle. It is often found inside the transmission pan, requiring the pan to be dropped to access it. In some vehicles, it might be located externally on the transmission case.
What tools do I need to diagnose/fix P0712 myself?
You'll need an OBD-II scanner to read and clear codes, a multimeter to test sensor resistance and circuit continuity, basic hand tools (wrenches, sockets), and potentially a transmission pan gasket and new transmission fluid if the sensor is inside the pan.
Is replacing the Transmission Fluid Temperature Sensor difficult?
The difficulty level is medium. If the sensor is externally mounted, it can be an easier fix. If it's located inside the transmission pan, it becomes more involved as it requires draining fluid, removing the pan, and refilling the transmission.
Could a P0712 code be caused by low transmission fluid?
While low transmission fluid can cause shifting problems and overheating, it's less likely to directly cause a 'low input' signal from the temperature sensor circuit. A low input typically points to an electrical issue with the sensor or its wiring, or the sensor itself failing.