P0940: Hydraulic Oil Temperature Sensor Circuit High
What to do
Gear changes may feel permanently slow and never sharpen up as the car warms. That specific pattern — slow from cold and still slow after an hour — points here rather than at the gearbox wearing out.
What this code means
The actuation hydraulic fluid temperature circuit reads above its valid range — an open circuit or a short to supply. Since these thermistors increase resistance as they cool, the module reads this as fluid that is impossibly cold and applies the conservative actuator timings it uses for a cold system.
The result is gear changes that stay slow and deliberate no matter how long the car is driven, which owners tend to describe as the gearbox having become lazy rather than as a fault.
Likely causes
Start here
- Open circuit in sensor wiring · moderate
- Corroded transmission connector · moderate
- Faulty hydraulic oil temperature sensor · moderate
Less common
- Wiring shorted to voltage · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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