Engine Coolant Temperature Sensor 1
The engine coolant temperature sensor is out of range.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine coolant temperature sensor measures how hot the engine coolant is; if it reads too high or too low, it indicates a problem that can affect engine performance.
What the computer is actually seeing
The ECM monitors the coolant temperature to optimize fuel injection and ignition timing. It expects a signal voltage between 0.5V (cold) and 4.5V (hot). Any voltage outside this range raises an error.
What a healthy reading looks like
Coolant temperature should be between 180°F and 220°F (82°C to 104°C); sensor voltage should be between 0.5V and 4.5V.
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; ensure it's full and there's no leak.
- 2Inspect the wiring and connector to the coolant temperature sensor for damage or corrosion.
- 3Measure voltage at the coolant temperature sensor connector with a multimeter; expect 0.5V to 4.5V.
- 4If voltage is outside the expected range, replace the coolant temperature sensor and recheck.
- 5If the voltage is normal but the code persists, inspect PCM to ensure it functions correctly.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or short circuits
- Coolant leaks affecting sensor operation
- Faulty ECM (rare)
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It is safe to drive but check coolant levels and performance issues soon.
Will this code come back after clearing?
If the problem isn't fixed, yes, the code will likely return.
Why does it pair with SPN 110?
SPN 110 often indicates a related issue with the coolant temperature affecting performance.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →