OBD-II code · Powertrain (generic)
P0939 Hydraulic Oil Temperature Sensor Circuit Low
The hydraulic oil temperature sensor reports a circuit low fault. Oil temperature feedback for hydraulic system is unreliable.
Is it safe to drive with P0939?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyTemperature sensor failed
- PossibleWiring fault
- Less likelyConnector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Hydraulic Oil Temp Sensor, Wiring Harness, Tcm
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.