P0198
Engine Oil Temperature Sensor High
If your code reader dashboard displays the generic DTC error code P0198, your vehicle is currently experiencing an active failure related to "Engine Oil Temperature Sensor High". Proper system troubleshooting is required to safely clear this warning.
Driver's Summary
Code P0198 means your vehicle detected a problem with the engine oil temperature sensor high system. The most common signs are cooling fans run constantly, warning message on dash, limp mode. You can typically drive short distances, but ignoring this code long-term will cause accelerated component wear and higher repair costs.
Symptoms
Cooling fans run constantly, warning message on dash, limp mode
Common Causes
- Short to voltage in EOT circuit
- Open circuit or unplugged sensor
- Failed EOT sensor
- Actual engine overheating condition
How to Fix
- 1 Repair short to battery voltage
- 2 Plug in sensor or repair broken wire
- 3 Replace EOT sensor
- 4 Check coolant level and cooling system
Technical Explanation
P0198 is stored after the control module confirms the fault over multiple ignition cycles, ruling out transient electrical noise as the cause. The diagnostic runs during closed-loop operation only, ensuring the engine is at full operating temperature and the PCM's fuel trim feedback loop is active before confirming any out-of-range condition. After two failed drive cycles, the code transitions from a pending to a confirmed DTC, and the PCM activates the MIL. Clearing the code without repairing the fault will result in re-illumination within one to two complete drive cycles.
Is It Safe to Drive?
Medium-severity fault: the car functions but not optimally. The short to voltage in eot circuit issue will not resolve itself and will cause measurable long-term wear. A repair in the $50–$300 range now avoids far higher costs later.
Mechanic's Pro Tip
The most common mistake with P0198 is replacing the sensor without verifying the reference voltage and ground integrity first. Use a scan tool to monitor the sensor's live output; a truly failed sensor shows a stuck, flatlined reading — a sensor that fluctuates but reads slightly off usually indicates a wiring or vacuum issue, not a dead sensor. Always spray electrical contact cleaner on the connector pins before condemning the sensor.
Wiring repair: 100; EOT sensor: 80 - 200