P0939Hydraulic Oil Temperature Sensor Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The hydraulic oil temperature sensor signal sits below its valid window. With the usual NTC thermistor, a low voltage corresponds to an implausibly hot reading and typically comes from a signal wire shorted to ground or a sensor shorted internally. Ferrari uses P0939 on its DCT for the radiator outlet and gearbox inlet oil temperature sensor, described as signal too low and read in the NCR gearbox ECU. CARB requires out-of-range checks on transmission sensors. P0940 is the high counterpart, P0937 the general circuit fault, P0938 plausibility and P0941 intermittent. Because the module believes the oil is very hot, it may reduce torque, change shift strategy or show an overheat warning.
- What you may notice
- Gearbox warning or overheat message
- Reduced performance or altered shift behaviour
- Likely causes
- LikelySensor signal wire shorted to ground
- PossibleTemperature sensor shorted internally
- RareControl module input fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.