Engine Oil Temperature Sensor Circuit Range/Performance
What it means
The engine computer has found that the oil temperature reading is implausible compared with what it expects, such as differing greatly from coolant temperature after a long soak, or not rising normally as the engine warms. The cause is usually a drifting sensor or a poor connection, and sometimes a truly abnormal engine temperature.
Related lights
Dashboard lights that may come on with this code.
Symptoms4
- Check engine light on.
- Oil temperature reading that does not change or changes unusually slowly.
- Oil change reminder may be inaccurate.
- Usually no clear driving symptoms.
Possible causes5
- Oil temperature sensor reading drifting with age.
- Extra resistance in the connector from oil or corrosion.
- Wrong reading from the coolant temperature sensor the computer compares against.
- Thermostat stuck open, slowing engine warm-up.
- Low oil level or real engine overheating (less common).
How to diagnose5
- Check the oil level and condition first.
- After the engine has sat overnight, compare oil temperature with coolant and air temperatures; a large difference points to the drifting sensor.
- Watch both readings as the engine warms; if both warm slowly, suspect a thermostat stuck open.
- Confirm the coolant temperature sensor is correct before condemning the oil sensor.
- Inspect the connector and measure sensor resistance against the manufacturer chart.
How to fix5
- Top up or change the oil if it is low or degraded.
- Clean the connector and fix the source of oil reaching it.
- Replace the thermostat if it is stuck open.
- Replace the oil temperature sensor if it is off the chart.
- Clear the codes and confirm the readings agree after a cold start and a full drive.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 100–600 (≈ USD 27–160)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
Topping up oil or cleaning the connector costs little; the cost rises with a new sensor, especially if the oil must be drained, or with a thermostat replacement.
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
Could the thermostat be the cause?
Sometimes. If it is stuck open the engine warms slowly, so oil temperature lags behind what the computer expects, and a code such as P0128 may appear too.
Should I replace the sensor right away?
Check the oil level, the connector and the coolant temperature sensor first, because the computer compares them and the fault may not be in the oil sensor.
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