P0198
Engine Oil Temperature Sensor A Circuit High
Engine oil temperature sensor
Generic OBD-II
Low
What it means
P0198 means the engine oil temperature sensor signal is too high, which corresponds to an implausibly cold reading — usually an open circuit, a short to voltage, or a failed sensor. It's a sensor-signal fault: the ECM substitutes a value, so the engine typically keeps running normally, though temperature-based functions like cooling fans or shift timing may be slightly affected until it's repaired.
Low
Can I keep driving? Usually still drivable — this is a temperature-sensor signal fault; the ECM substitutes a value, so drivability is normally unaffected.
Common symptoms
What you'll notice
- Check-engine light on
- Often no noticeable driving symptom
- Oil temperature reads implausibly low/cold on a scan tool
- Possible effect on cooling-fan or shift logic on some vehicles
Common causes
Most likely first
- Faulty engine oil temperature sensorLikely
- Signal wire open or shorted to voltageCommon
- Loose or corroded electrical connectorCommon
- Poor sensor groundLess often
- Faulty ECM (rare — confirm the sensor and wiring first)Less often
How to diagnose & fix
Work through it in order
- Read the live oil-temperature value and compare it to actual engine temperature — a circuit-high fault reads out of range.
- Inspect the sensor connector and wiring for an open or a short to voltage.
- Check the sensor's ground and reference circuit with the key on.
- Back-probe the signal wire to decide whether the sensor or the wiring is at fault.
- Replace the engine oil temperature sensor if it reads out of range with good wiring, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0198?+
In most cases yes. It's an oil-temperature signal fault and the ECM uses a default value, so the engine still runs normally. Fix it to keep temperature-based logic accurate.
Can I just clear P0198?+
It returns until the sensor or wiring is repaired. Clearing alone only resets the light temporarily.
Related codes
Often seen with P0198
Read & clear P0198 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX