Transmission Fluid Temperature Sensor A Circuit Low
What it means
The computer has seen the transmission fluid temperature sensor signal voltage below the allowed limit. On most designs the voltage falls as temperature rises, so a scan tool usually shows a false, very high temperature. The common cause is a wire shorted to ground or a failed sensor.
Symptoms4
- Check engine light on.
- Scan tool shows a very high fluid temperature even when the car is cold.
- Harsh or early shifts, or the transmission in a protection mode.
- Changed torque converter clutch lockup behavior.
Possible causes5
- Sensor signal wire shorted to ground inside or outside the transmission.
- Internal sensor failure.
- Fluid or water inside the connector causing electrical leakage.
- Internal transmission harness damaged by heat or rubbing.
- A fault in the transmission control module (rare).
How to diagnose5
- Compare fluid temperature with engine coolant temperature on a cold car; a very high reading confirms the fault.
- Unplug the transmission connector and watch the reading; if it moves to the lowest possible value, the short is usually inside the transmission or sensor.
- Inspect external wiring for rubbing against the body or exhaust.
- Measure sensor resistance at the connector and compare with the manufacturer table at the current temperature.
- Check insulation between the signal wire and ground.
How to fix5
- Clean and dry the connector, and replace its seal if fluid is getting in.
- Repair the shorted section of external wiring.
- Replace the fluid temperature sensor or the internal harness that carries it.
- Refill the transmission fluid to the correct level after any pan removal.
- Clear the codes and confirm the reading matches engine temperature when cold.
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 an internal sensor or internal harness is replaced along with fluid.
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
The scan tool shows very hot fluid. Is it real?
Usually not. With this code the reading comes from a low circuit voltage. Compare it with engine temperature on a cold car to be sure.
Does the transmission need to come out?
No. If the fault is internal, on many designs removing the pan is enough to reach the sensor or harness.
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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