Coolant Temperature Sensor 1 - Voltage Above Normal
Indicates the engine coolant temperature sensor is reporting high voltage values.
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What it means (plain English)
The coolant temperature sensor measures how hot the engine coolant is. If the sensor sends a voltage signal that’s higher than expected, it means it thinks the engine is hotter than it really is.
What the computer is actually seeing
The Engine Control Module (ECM) sees a voltage above the normal range (typically above 4.5 volts) from the coolant temperature sensor, suggesting that the coolant is too hot when it might not be.
What a healthy reading looks like
Normal coolant temperature voltage should be between 0.5V (for -40°C/-40°F) to 4.5V (for 125°C/257°F) depending on sensor range.
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 wiring harness and connections to the coolant temperature sensor for damage or corrosion.
- 2Verify coolant levels are within the proper range; should be between the 'LOW' and 'FULL' markings on the reservoir—add if needed.
- 3Measure the voltage at the coolant temperature sensor connector while the engine is running; should be between 0.5V and 4.5V. If above 4.5V, replace the sensor.
- 4Inspect the sensor for physical damage or contamination. If clean and undamaged, test the sensor resistance at different temperatures to see if it deviates from specifications.
Common causes
- Wiring issue between sensor and ECM
- Faulty coolant temperature sensor
- Corroded connector terminals
- Coolant levels too low or overfilled
- ECM malfunction
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's usually safe to drive, but if the temperature readings are inaccurate, it could lead to overheating issues.
Will this code come back after clearing?
Yes, if the underlying issue isn't resolved, the code will likely return.
Why do I also see SPN 3062 with this code?
SPN 3062 often appears together due to the system seeing multiple related faults with the coolant temp sensor or wiring.
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