The hydraulic oil temperature is closely monitored by the ECU, allowing it to make adjustments on the fly to prevent overheating. If there is an abnormally high voltage signal in the hydraulic oil temperature sensor circuit, this temperature data will be compromised and a DTC P0940 will be triggered.
How severe is the code?
The diagnostic code P0940 is quite serious, as it means the ECU does not know the current temperature of the hydraulic oil. This can obviously lead to overheating, which may result in severe/expensive damage.
Symptoms
Symptoms of a P0940 include:
- Check engine light
- Overheating
- Irregular vehicle behavior
- Limp mode
Causes
- Damaged/corroded wiring and/or connectors
- Faulty hydraulic oil temperature sensor
- Low hydraulic fluid
- Dirty hydraulic fluid/filter
How to diagnose the code?
Diagnosing an OBDII fault code P0940 should start with checking the condition of the hydraulic oil (if it is dirty, it will need to be changed). The wiring and connectors along the hydraulic oil temperature sensor circuit should then be closely inspected for signs of damaged wires and corroded or broken connectors. The sensor itself may also need to be tested, possibly along with the ECU.
What repairs will fix P0940?
- Repair damaged wiring and/or connectors
- Replace the hydraulic oil temperature sensor
- Change the hydraulic fluid
- Reprogram or replace the ECU