Engine Oil Temperature Sensor Low
What does P0197 mean?
The P0197 code means the vehicle's onboard diagnostic system has detected: Engine Oil Temperature Sensor Low. This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Oil temperature reads excessively high on scan tool
- Cooling fan may run continuously
- Transmission may avoid higher gears (protective mode)
- Possible reduced engine performance
Probable Causes (Ranked by Likelihood)
- Shorted oil temperature sensor (internally or to ground) Very High
- Short to ground in the sensor wiring High
- Corroded connector with water bridging pins Moderate
- Damaged wiring insulation touching metal Moderate
- PCM input fault Low
Step-by-Step Diagnostic Procedure
-
Read oil temperature on a scan tool. A reading of 280+ degrees F with the engine cold confirms a low circuit (shorted) condition.
-
Disconnect the sensor. If the reading jumps to -40 degrees F, the sensor is shorted internally.
-
With the sensor disconnected, check the signal wire for a short to ground (should be infinite resistance to ground).
-
Inspect the connector for moisture, corrosion, or contamination that could short the pins.
-
Check wiring insulation for damage where it contacts engine components.
Frequently Asked Questions
Can I drive with code P0197?
You can drive short distances, but systems that rely on oil temperature may behave abnormally. The cooling fan may run non-stop and the transmission may stay in lower gears as a protective measure.
Why does low circuit mean high temperature?
Oil temperature sensors use NTC (Negative Temperature Coefficient) thermistors. Lower resistance equals lower voltage equals higher temperature reading. A short to ground mimics very low resistance, making the PCM think the oil is extremely hot.
Will a low circuit cause the engine to overheat?
No. The actual oil temperature is fine -- only the sensor reading is wrong. The cooling fan may run unnecessarily, but this will not cause overheating. However, transmission shift patterns may be affected.