Engine Coolant Temperature Sensor Circuit
Problems with the engine coolant temperature sensor circuit detected.
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What it means (plain English)
The engine coolant temperature sensor measures how hot the engine coolant is. If it’s sending bad data to the computer, the engine might run poorly or use too much fuel.
What the computer is actually seeing
The Engine Control Module (ECM) monitors voltage from the coolant temperature sensor, usually between 0.5V (cold) to 4.5V (hot). If it sees a voltage outside this range, say 0V or over 5V, it triggers the fault code.
What a healthy reading looks like
Coolant temperature should read between 180°F and 220°F (82°C to 104°C) when the engine is fully warmed up, with sensor voltage typically around 2.5V to 3.5V.
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.
- 1Check the engine coolant level; if low, refill and retest.
- 2Inspect wiring and connectors for corrosion, damage, or loose connections.
- 3Test the engine coolant temperature sensor with a multimeter; should have resistance values according to temperature (e.g., 2200 ohms at 32°F/0°C, 130 ohms at 212°F/100°C).
- 4Compare sensor reading to actual coolant temperature using a scan tool; if it’s more than 10° off, replace sensor.
- 5Clear the code and test drive the vehicle to see if the code returns.
Common causes
- Faulty engine coolant temperature sensor
- Damaged wiring or connectors
- Coolant leaks affecting sensor
- ECM software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable, but you might experience poor engine performance or increased fuel consumption.
Will this code come back after clearing it?
If the issue isn't fixed, the code will most likely reappear.
Why does this code often pair with SPN 110?
SPN 110 is for oil temperature, and both can indicate overall engine cooling performance issues.
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