P0712: Transmission Fluid Temperature Sensor A Circuit Low Input

What Does The P0712 Code Mean?

The transmission fluid temperature sensor (TFT) sensor produces a signal that is used by the powertrain control module (PCM) to determine shift points, line pressure and torque converter clutch (TCC) control. The sensor is often located in the transmission oil pan.

The TFT sensor receives a reference voltage (usually 5 volts) from the PCM. It the varies its internal resistance in relation to transmission fluid temperature to send a return voltage signal to the PCM. TFT sensors are a type of negative temperature coefficient (NTC) thermistor. This means internal resistance of the sensor is inversely proportional to the oil temperature. The TFT sensor signal voltage goes down when the transmission fluid temperature goes up and vice versa.

Code P0712 is set when the PCM detects a low transmission fluid temperature sensor signal. This usually indicates the circuit is shorted.

P0712 wiring diagram

Related trans fluid temperature sensor “A” circuit codes:

• P0710 Transmission Fluid Temperature Sensor A Circuit Malfunction
• P0711 Transmission Fluid Temperature Sensor A Circuit Range/Performance
• P0713 Transmission Fluid Temperature Sensor A Circuit High Input
• P0714 Transmission Fluid Temperature Sensor A Circuit Intermittent

What Are The Symptoms Of The P0712 Code?

Symptoms of a P0712 engine code may include:

• Illuminate check engine light
• Improper torque converter clutch operation
• Harsh or delayed shifts
• Vehicle stuck in limp mode

What Are The Potential Causes Of The P0712 Code?

Causes for this trouble code may include:

• Faulty transmission fluid temperature sensor
• Transmission problems
• Wiring problems
• Faulty PCM

How Serious Is This P0712 Code?

The severity of this code is moderate to severe. In some cases, this code can indicate a transmission problem. It’s a good idea to address this code as soon as possible.

How Can You Fix The P0712 Code?

Begin by visually inspecting the transmission fluid temperature sensor and the corresponding wiring. Look for loose connections, damaged wiring, etc. If damage is found, repair as necessary, clear the code and see if it returns.

Next, check for technical service bulletins (TSBs) regarding the issue. If nothing is found, you will need to move forward to step by step diagnosis of the system.

The following is a generalized procedure, as testing for this code varies between vehicles. To accurately test the system, you’ll want to refer to the manufacturer’s diagnostic flow chart.

Do Some Preliminary Circuit Testing

Use a scan tool to monitor the transmission temperature sensor data parameter. Disconnect the TFT sensor; the scan tool value should drop to a very low value. Next, connect a jumper wire across the terminals.

If the scan tool now displays a very high temperature, the connections are sound and the ECM can recognize the input. This means the problem is most like the sensor and not a circuit or PCM problem.

Test The Sensor

Disconnect the transmission fluid temperature sensor connector. Next, measure the resistance between the two sensor terminals using a digital multimeter set to ohms. Start the engine and watch the meter value; the values should decrease smoothly as the engine warms up (check the engine temperature gauge on the dash to ensure the engine reaches operating temperature). If engine temperature increases but TFT resistance does not decrease, the sensor is faulty and should be replaced.

Check The Circuit

Check the reference voltage side of the circuit: with the ignition on, use a digital multimeter set to volts to check for a 5-volt reference from the PCM at one of the two transmission fluid temperature sensor terminals.

If no reference signal is present, connect the meter set to ohms (with the ignition off) between the reference voltage pin on the TFT and the reference voltage pin on the PCM. If the meter reads out of limits (OL) there is an open circuit between the PCM and sensor that will need to be located and repaired. If the meter reads a numeric value, there is continuity.

If everything is good up to this point, you’ll want to check that there is 5-volts coming out of the PCM at the reference voltage terminal. If there is not a 5-volt reference from the PCM, the PCM is probably faulty.

Check The Ground Side Of The Circuit

Connect the meter set to ohms (with the ignition off) between the ground terminal on the transmission fluid temperature sensor and the ground terminal on the PCM. If the meter reads out of limits (OL) there is an open circuit between the PCM and sensor that will need to be located and repaired. If the meter reads a numeric value, there is continuity.

Finally, check that the PCM has a good ground by attaching one meter lead to the PCM ground terminal and the other to chassis ground. Once again, If the meter reads out of limits (OL) there is an open circuit between the PCM and ground that will need to be located and repaired.

If everything in the circuit checks out, there may be a problem with the transmission. This is especially true if the transmission fluid temperature codes are set along with other transmission codes.

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> Transmission Fluid Temperature Sensor
>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> Transmission Parts
>>> ECU
>>> INNOVA 5210
>>> KAIWEETS Digital Multimeter

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

P0712 Trans Fluid Temp Sensor A Circuit Low Input, OBD-Codes.