P0198 Code Meaning and Next Steps

First checks take 10 minutes for basic checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!There is overheating, steam, or a visible coolant leak.
!The temperature gauge moves toward hot or the engine starts running much worse than normal.

If the light is steady and the vehicle still drives normally: Often yes for a short time, but it should not be ignored if drivability changes are obvious.

What to check first

Step-by-step checks

1
Safety first
Let the engine cool before inspecting the sensor, connector, or any hot oil-area components
2
Free - no tools
Check whether the reading is pegged hot or behaves strangely on a cold start
3
Basic tool needed
Inspect the connector and harness for an open circuit, corrosion, or heat damage
4
Basic tool needed
Look for recent oil-filter or engine-bay work that may have pulled the wiring loose
5
Basic tool needed
If scan data is available, compare the oil temperature value with the actual engine state before buying parts
6
Basic tool needed
If the vehicle also shows overheating symptoms, treat those separately and do not assume the sensor is the only fault

If the code returns

-If the signal is stuck high, an open circuit or failed sensor is more likely than oil condition alone.
-If the reading changes when the harness is moved, focus on wiring before replacing the sensor.
-If the code only appears hot and not cold, suspect a heat-sensitive harness or sensor.

Background

What this code means

P0198 is a generic OBD-II code for a high-input engine oil temperature sensor signal.

That often means the ECU is seeing a signal that suggests the oil is much hotter than expected, or the circuit is open and defaulting to an extreme value. The problem is usually electrical before it is a true oil-temperature event.

Diagnosis

Common causes

Most common

Open circuit in the sensor signal

A broken wire or loose terminal can make the ECU see a very high value.

Common

Failed oil temperature sensor

The sensor may have drifted high or failed internally.

Common

Connector or harness heat damage

Heat can damage the wiring or terminals and create an unrealistic hot reading.

Possible

Connector corrosion or contamination

Oil intrusion or corrosion can interfere with the signal and make it look too high.

Avoid these mistakes

What not to do

xDo not replace the sensor before checking for an open circuit or obvious connector damage.
xDo not inspect hot engine components without letting them cool first.

Parts

Parts that may need replacing

PartTypical costNotes

Engine oil temperature sensor$20-$90Most relevant when the circuit is intact but the signal is still implausibly high.

Connector or wiring repair$20-$160Often the right fix when the signal is open or intermittently lost.

Heat-shield or routing repairVariesUseful when the harness is being cooked by nearby heat or moving parts.

Related OBD codes

P0195

P0195 means the engine oil temperature sensor circuit is not working properly.

P0196

P0196 means the engine oil temperature sensor is reading outside the expected range.

P0197

P0197 means the engine oil temperature sensor is reading too low.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0198 was seeded from dtcdb and then expanded around high-input engine oil temperature faults, especially open circuits, sensor drift, and heat damage.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0198 - The Engine Oil Temperature Sensor Is Reading Too High