P0712 Code: Transmission Fluid Temperature Sensor A Circuit Low

What the P0712 code means

The sensor measures the temperature of the transmission fluid. The computer uses it to adjust pressure, shift smoothness and torque converter lockup, and to protect the transmission from overheating.

The sensor changes its resistance with temperature, and the computer measures the resulting voltage. A low signal is usually caused by the signal wire shorted to ground or by a missing reference voltage. That is what sets the P0712 code.

Without this signal the computer uses a fixed value, so shifts can be harsh when cold or the torque converter may not lock up. On many transmissions the sensor is part of the internal harness, so it is replaced by removing the pan. See the sensor guide to learn how to test it.

To confirm the fault, unplug the component with the key on and watch what happens to the reading or the code. If the value jumps to the opposite extreme, the wiring is fine and the component is the part pulling the signal to ground. If nothing changes, look for the short in the wire itself, starting where the harness rubs against the engine, the chassis or the exhaust.

P0712 code symptoms

• Check engine light on.
• Harsh shifts or a torque converter that does not lock up.
• Harsh shifts when the transmission is cold.
• Engine rpm a little high on the highway.

Likely causes of the P0712 code

1. Signal wire shorted to ground by the harness rubbing the engine, the chassis or a bracket.
2. Shorted supply reference. If several sensors fail at once, suspect the shared reference.
3. Damaged sensor with an internal short.
4. Connector with water or corrosion, which creates a path to ground.

How to diagnose the P0712 code step by step

1. Read the sensor value on the scan tool and compare it with what is expected.
2. Inspect the connector for corrosion, water and loose pins.
3. Check power and ground with the key on: a correct reference and less than 0.1 volt drop on the ground.
4. Measure the signal with the connector plugged in and see whether it changes with the condition.
5. Do a wiggle test of the wiring with the scan tool in graph mode.
6. Check the continuity of each wire back to the computer (under 1 ohm).
7. With the transmission cold, compare its temperature with the coolant temperature. They should be close to each other.

How to fix the P0712 code

• Repair the connector or the wiring.
• Replace the sensor if the tests confirm it is bad.
• Correct the real condition if there is one.
• Clear the P0712 code and verify with a road test.

Technical reference data

• NTC thermistor: high resistance when cold and low resistance when hot.
• Normal fluid temperature: 70 to 95 °C (158 to 203 °F).
• Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

The source notes how the sensor is mounted on two brands.

P0712 on GM

On GM the sensor is built into the internal harness of the transmission or into the control module.

P0712 on Ford

On Ford the sensor is built into the internal harness of the transmission or into the control module.

Frequently asked questions about P0712