Engine Oil Temperature Sensor Signal Out of Range
The P1189 code indicates that the engine control module (DME/ECM) has detected an oil temperature sensor signal that is outside the expected range during the self-test routine. This means the sensor reading is irrational—too high, too low, or not changing as expected based on the engine's thermal model when compared to coolant temperature and runtime.
01. Most Common Causes
- Faulty engine oil temperature sensor (open circuit, short circuit, or signal drift)
- Damaged, corroded, or shorted wiring or connector to the oil temperature sensor
- Stuck oil thermostat or thermal control valve affecting actual oil temperature
- Incorrect engine oil level or severely degraded oil
- Internal engine control module (DME) failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible poor engine performance or reduced fuel economy
03. Step-by-Step Diagnosis
Scan for additional codes and freeze frame data
Visually inspect oil temperature sensor wiring and connector for damage or corrosion
Measure sensor resistance and compare to specifications at known oil temperatures
Check engine oil level and condition
Verify oil thermostat operation if applicable
If all else fails, test or replace the engine control module
1. Frequently Asked Questions
Is it safe to drive?▼
You can usually drive short distances, but prolonged driving may cause engine damage due to incorrect oil temperature readings affecting engine management. Have it diagnosed soon.
How much does it cost to fix?▼
Typically $150 to $400 for sensor replacement, including parts and labor. Wiring repairs or ECM replacement can cost more.