P0198

Engine Oil Temperature Sensor Circuit High

Car Fault Codes Cooling & lubrication

Can you still drive? Yes, normally

Who can fix it? DIY with some experience

Typical repair time 20 minutes – 2 hours

Typical cost SAR 100 to 600

What it means

The engine computer has seen the oil temperature sensor signal voltage rise above the maximum allowed. In most designs this is read as a very low oil temperature, and the usual cause is an open circuit such as an unplugged connector, a broken wire or an internally open sensor.

Symptoms4

Check engine light on.
Very low, fixed oil temperature reading even after warm-up.
Oil change reminder may be inaccurate.
Usually no clear driving symptoms.

Possible causes5

Unplugged or loose connector, especially after an oil change or work under the engine.
Broken signal or ground wire.
Open circuit inside the oil temperature sensor.
Corroded connector terminals causing high resistance.
Signal wire shorted to a voltage source (less common).

How to diagnose4

Watch the reading on a scan tool; a very low reading that does not rise as the engine warms confirms the high voltage.
Check the connector is seated, especially after recent work under the engine.
Place a temporary jumper between the signal and ground terminals on the harness side; if the reading jumps to very hot, the wiring is good and the sensor is open.
If the reading does not change, check wiring continuity to the computer using the manufacturer wiring diagram.

How to fix4

Reconnect the connector or clean its terminals.
Repair the broken wire.
Replace the oil temperature sensor if its internal circuit is open.
Clear the codes and confirm the reading rises normally as the engine warms.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

Reconnecting a connector or repairing a wire is cheap; the upper end is for a new sensor, especially if the oil must be drained or it is combined with the oil level sensor.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

The code appeared after an oil change. Why?

The connector may have been disturbed or unplugged during work under the engine, so check it before buying any part.

Why does the scan tool always show cold oil?

Because an open circuit pushes the voltage to its maximum, which most designs interpret as a very low temperature.

This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

Report a mistake

Spotted something inaccurate? Tell us and we will review and correct it.