Engine Coolant Temperature Sensor Circuit High Input
The engine's coolant temperature sensor is reporting a high voltage signal.
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What it means (plain English)
The coolant temperature sensor tells the computer how hot the engine is. If it sees a voltage reading that’s too high (usually above 4.9 volts), it thinks there's something wrong, so it triggers the check engine light.
What the computer is actually seeing
The engine control module (ECM) sees a voltage reading from the coolant temperature sensor that's higher than expected, indicating a potential short circuit or sensor fault.
What a healthy reading looks like
Normal voltage from the coolant temperature sensor should be 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.
- 11. Check the wiring and connectors at the coolant temperature sensor for damage or corrosion. If damaged, repair or replace them. Decision: If wiring looks good, proceed to step 2.
- 22. Measure the voltage at the coolant temperature sensor connector with the engine off. Expected value should be close to 0 volts. High voltage indicates a short. Decision: If voltage is high, check for wiring shorts. If normal, replace the sensor.
- 33. If replacing the sensor, check coolant level. Ensure it’s adequate. If coolant is low, refill and recheck. If not low, install new sensor and clear codes.
Common causes
- Short circuit in wiring or connectors to the coolant temperature sensor
- Faulty coolant temperature sensor
- Engine coolant temperature too high due to overheating issues
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Driving with this code can lead to engine overheating, so fix it soon.
Will this code come back?
If the underlying issue isn't resolved, like a short circuit or bad sensor, yes, it will likely come back.
Why does this code show up with other codes?
It's common for multiple codes to trigger if there's a problem in the same circuit or system.
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