Engine Oil Temperature Sensor Circuit High (Subaru)
What does P1183 mean?
The P1183 code means the vehicle's onboard diagnostic system has detected: Engine Oil Temperature Sensor Circuit High (Subaru). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Oil temperature reads abnormally low on scan tool
- Extended warm-up fuel enrichment
- Poor fuel economy during warm-up
- Possible rough running during warm-up
Probable Causes (Ranked by Likelihood)
- Open circuit in oil temperature sensor wiring Very High
- Failed oil temperature sensor (open element) High
- Disconnected sensor connector Moderate
- Corroded sensor ground connection Moderate
- ECM input circuit fault Low
Step-by-Step Diagnostic Procedure
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Check oil temperature sensor data on a scan tool (high voltage = cold reading)
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Inspect the sensor connector for secure connection
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Measure sensor resistance at current temperature (should decrease as temp rises)
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Check wiring continuity from sensor to ECM
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Replace the sensor if resistance is open or out of specification
Frequently Asked Questions
What does high circuit mean for P1183?
High circuit means the ECM is seeing higher-than-expected voltage from the oil temperature sensor, which it interprets as very cold oil. This causes the ECM to run a richer fuel mixture for longer than necessary.
Can I drive with P1183?
You can drive short distances. The engine will run richer than needed, which wastes fuel and can foul spark plugs over time. The vehicle should be repaired within a reasonable timeframe.
Is this related to the Subaru head gasket issue?
Not directly. P1183 is an electrical fault with the oil temperature sensor circuit. However, if a head gasket leak is contaminating the oil or causing unusual temperatures, it could indirectly affect sensor readings.