P0197 Engine Oil Temperature Sensor Low

P0197 indicates the engine oil temperature sensor signal is low. The circuit is below expected voltage or reporting oil temperature too cold.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not diagnose true low oil temperature until the low sensor circuit and connector condition are verified.

Symptoms of P0197

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0197

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Measure oil temperature sensor signal voltage, reference, ground, and resistance while checking for short-to-ground faults.
Compare oil temperature with coolant, ambient, intake temperature, and actual warm-up behavior after a cold soak.
Inspect connector oil intrusion, harness rub points, shared reference faults, and freeze-frame voltage or temperature data.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.