Engine Coolant Temperature Sensor Circuit High
Indicates that the engine coolant temperature sensor signal is too high.
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What it means (plain English)
The engine's computer is seeing a coolant temperature reading that is above what it expects, which could mean the engine is overheating or the sensor is faulty.
What the computer is actually seeing
The engine control module (ECM) monitors the voltage signal from the coolant temperature sensor. A high voltage (typically above 4.5 volts) indicates a fault. Normal operation usually sees values around 0.5 to 4.5 volts depending on the coolant temperature.
What a healthy reading looks like
Coolant temperature should typically range from 180°F (82°C) to 220°F (104°C) for normal operation.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check engine coolant level; low coolant can cause incorrect temperature readings. If low, fill and retest.
- 22. Inspect the wiring and connectors to the coolant temperature sensor. Look for signs of wear, corrosion, or loose connections. Repair as necessary.
- 33. Use a scanner to monitor the coolant temperature reading. Compare it to actual engine temperature using a reliable thermometer. If they differ significantly, proceed to step 4.
- 44. Test the engine coolant temperature sensor with a multimeter. At room temperature (68°F), it should read approximately 2.5 to 3.5 volts. If it reads above 4.5 volts, replace the sensor.
- 55. If the sensor is good, check for faults in the ECM or related wiring. Conduct a continuity test and verify ground connections.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issue or short in the coolant temperature sensor circuit
- ECM malfunction
- Poor ground connection
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
Moderate severity means you can drive but keep an eye on engine temperature; fix it soon.
Will this code come back after erasing it?
If the underlying issue isn't fixed, the code will likely return.
Why does this code sometimes pair with SPN 110?
SPN 110 relates to engine over-temperature, so often they present together due to related cooling system issues.
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