Engine Coolant Temperature Sensor 2 Circuit Low
What does P2186 mean?
The P2186 code means the vehicle's onboard diagnostic system has detected: Engine Coolant Temperature Sensor 2 Circuit Low. This is a moderate severity code.
Common Symptoms
- Temperature gauge reading abnormally hot
- Cooling fans running constantly
- Engine running lean (too little fuel)
- Poor cold-start performance
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Faulty engine coolant temperature sensor 2 (shorted) Very High
- ECT sensor 2 signal wire shorted to ground High
- Corroded ECT sensor 2 connector causing short circuit Moderate
- Coolant leak contaminating sensor connector Moderate
- PCM input circuit pulled low Low
Step-by-Step Diagnostic Procedure
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Check ECT sensor 2 reading on scan tool -- compare to actual temperature with an infrared thermometer
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Inspect sensor connector for coolant contamination or corrosion causing a short
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Measure ECT sensor 2 resistance at known temperature -- should match the resistance vs temperature chart
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Disconnect sensor and check signal wire for shorts to ground
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Replace ECT sensor 2 if internally shorted (near 0 ohms resistance)
Frequently Asked Questions
Can I drive with code P2186?
You can drive short distances, but the PCM thinks the engine is very hot when it may not be. This can cause lean fuel mixtures (potential engine damage), cooling fans running all the time, and poor engine performance especially during cold starts.
Why are my cooling fans always on?
When the ECT sensor reads shorted low, it sends a signal indicating the engine is extremely hot. The PCM responds by running the cooling fans at full speed continuously to try to cool the engine, even though the actual temperature may be normal.
Can coolant leaking onto the sensor cause this?
Yes. Coolant leaking from a nearby connection or from the sensor itself can contaminate the electrical connector, creating a short circuit between the signal and ground pins. This causes the PCM to read a very low resistance, interpreting it as extremely high temperature.