The presence of a DTC P0938 means that the ECU believes the hydraulic oil temperature sensor is not operating within its preprogrammed range. This could naturally lead to overheating and serious internal damage.
How severe is the code?
The hydraulic oil temperature sensor monitors the heat of the hydraulic oil and constantly transmits this information to the ECU. Diagnostic code P0939 means this is not happening as it should, so overheating and other serious damage can occur.
Symptoms
Symptoms of a P0938 include:
- Check engine light
- Overheating
- Irregular vehicle behavior
- Limp mode
Causes
- Damaged/frayed wiring
- Connectors are corroded or broken
- Hydraulic oil temperature sensor has failed
- Low hydraulic fluid level
- Dirty hydraulic fluid and filter
How to diagnose the code?
To understand what is causing a P0938 OBDII fault code, a technician must check the condition of the hydraulic oil to see if it is dirty, low, burnt, or contains metal shavings. If any of these conditions apply, the fluid must be changed immediately. The wiring and connectors along the hydraulic oil temperature circuit should also be checked for signs of damage and corrosion. If no issues were detected, the hydraulic oil temperature sensor and possibly the ECU will need to be tested.
What repairs will fix P0938?
- Repair damaged wiring and/or connectors
- Replace the hydraulic oil temperature sensor
- Change the hydraulic fluid
- Reprogram or replace the ECU