Transmission Fluid Temperature Sensor A Circuit
What it means
The transmission fluid temperature sensor measures fluid temperature so the computer can adjust shift pressure, shift timing and torque converter clutch lockup. The computer has detected a fault in this sensor circuit, so it now uses a default value that can change how the shifts feel.
Symptoms4
- Check engine light on.
- Harsh or delayed shifts, especially when cold.
- Torque converter clutch not locking, so engine speed is slightly higher on the highway.
- Implausible or fixed transmission fluid temperature reading on a scan tool.
Possible causes5
- Corrosion or fluid inside the transmission connector the sensor circuit passes through.
- Open or shorted sensor wiring.
- A faulty sensor, which on many designs sits inside the transmission on the internal harness.
- Heat damage to the internal transmission harness.
- A fault in the transmission control module (rare).
How to diagnose5
- Compare the transmission fluid temperature with engine coolant temperature after the car has sat for a long time; they should be close.
- Watch the reading as the car warms up; it should rise gradually without jumps.
- Inspect the transmission connector for fluid, corrosion or loose pins.
- Measure sensor resistance at two different temperatures and compare with the manufacturer table.
- Check the wiring between the transmission and the module for opens or shorts.
How to fix5
- Clean the connector and repair the pins, and replace its seal if fluid is getting in.
- Repair damaged wiring outside the transmission.
- Replace the fluid temperature sensor, which may require removing the transmission pan on some designs.
- Replace the internal harness if the sensor is part of it.
- Clear the codes and confirm the temperature reading rises normally while driving.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low for a connector or external wiring repair, and higher when the sensor is inside the transmission or built into the internal harness and needs the pan removed and fluid added.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Does this code harm the transmission?
Not directly, but the computer loses the real fluid temperature, so shifts can become harsh and it cannot protect the transmission from overheating.
Where is the fluid temperature sensor?
It varies by vehicle. On many it sits inside the transmission on the internal harness or near the valve body, while on others it is external.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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