Engine Coolant Temperature Sensor 1 - Voltage Above Normal
Engine coolant temperature is too high according to the sensor reading.
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What it means (plain English)
The engine coolant temperature sensor is telling the computer that the coolant is too hot, which could mean your engine is overheating or the sensor itself is faulty.
What the computer is actually seeing
The computer reads a voltage signal from the coolant temperature sensor that should normally be around 0.5 to 4.5 volts. If it sees a voltage above 4.5 volts, it triggers this code.
What a healthy reading looks like
The normal voltage range for a functioning coolant temperature sensor is between 0.5V (cold) and 4.5V (hot).
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; add if low and check for leaks.
- 2Inspect the wiring and connectors to the coolant temperature sensor for damage or corrosion.
- 3Using a scan tool, monitor the coolant temperature sensor voltage while the engine is running; it should be between 0.5V and 4.5V under normal conditions.
- 4If voltage is over 4.5V, replace the engine coolant temperature sensor. If wiring is intact and sensor is operational, investigate potential overheating issues.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issues or damaged connector
- Coolant leak causing low fluid levels
- Faulty engine coolant thermostat
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderately severe; if the engine is truly overheating, it could cause damage, so fix it soon.
Will the code come back after clearing?
If the underlying issue isn't resolved, the code will likely return.
Why does this code pair with overheating issues?
A faulty sensor may indicate high temperatures, leading the computer to think the coolant is too hot when it may not be.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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