Engine Coolant Temperature Sensor - Voltage Above Normal Operating Range
Coolant temperature sensor circuit voltage is too high.
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What it means (plain English)
The engine has a sensor that measures how hot the coolant is. If that sensor sends back a higher voltage than it should, the computer thinks the engine is running hotter than it is, which can throw off performance.
What the computer is actually seeing
The Engine Control Module (ECM) expects a coolant temperature voltage between 0.5V (around 32°F) and 4.5V (around 248°F). Anything above 4.5V indicates a problem.
What a healthy reading looks like
0.5V to 4.5V at normal operating temperatures, ideally around 1.5V-2.5V when the engine is warm.
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. Inspect the wiring and connectors to the coolant temperature sensor; check for damage or corrosion.
- 22. Measure the voltage at the sensor connector with the engine at operating temperature; should be approximately 1.5V-2.5V.
- 33. If voltage is above 4.5V, disconnect the sensor and measure again; if voltage drops to normal, replace the sensor.
- 44. If voltage remains high, check for a short in the wiring harness or poor ground; fix as necessary.
Common causes
- Wiring short to power supply
- Faulty coolant temperature sensor
- Poor ground connection for the sensor
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code present?
It's advised to limit driving as inaccurate coolant readings can lead to overheating.
Will this code come back after I clear it?
If the underlying issue isn't fixed, like a bad sensor or wiring, it will return.
Can this code be related to other engine performance issues?
Yes, incorrect coolant temperature readings can impact fuel injection timing and emissions.
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