What does it mean?
P1179 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Oil Sensor Signal re Oil Temperature Implausible .
Symptoms
- Check engine light on with the fault stored
- Oil temperature shown on the instrument display is missing, frozen or clearly wrong
- Service interval calculation and oil condition monitoring stop working correctly
- Cooling fan or transmission strategies may behave differently than usual
- No obvious change in the way the engine runs in many cases
- Oil level warning messages may appear at the same time on vehicles with a combined sensor
Likely causes
- Failed temperature element inside the combined oil level and temperature sensor
- Oil level low or the sensor buried in sludge, so it never sees a representative oil temperature
- High resistance in the sensor wiring or a corroded, oil-soaked connector
- Signal wire shorted to another circuit or to ground within the sump harness
- Sensor loose in its mounting or the sealing ring leaking, leaving the element partly out of the oil
- Severely degraded or diluted oil that changes the sensor's electrical behaviour
- Rarely, a control module input or software calibration issue
How to fix it
- Verify oil level and condition; low or heavily contaminated oil is a frequent trigger
- Compare the oil temperature reading with coolant temperature in live data after a long cold soak; both should be close to ambient
- Warm the engine and watch whether oil temperature rises smoothly and plausibly
- Unplug the sensor and measure the temperature element resistance, comparing it with the temperature-resistance table for that sensor
- Check the harness for continuity and for a short to ground, and inspect the connector for oil migration and corrosion
- Confirm the sensor is correctly seated and sealed in the sump
- Replace the oil condition sensor if its element is out of specification, then clear the code and verify a plausible warm-up curve