Engine Coolant Temperature Sensor Circuit High
The engine coolant temperature sensor is reporting a high voltage signal.
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What it means (plain English)
The engine coolant temperature sensor measures how hot your engine cooling liquid is. If it's sending a signal that's too high, the engine thinks it's hotter than it really is, which can cause poor performance and even damage.
What the computer is actually seeing
The engine control module (ECM) expects a voltage between 0.5V (cold) and 4.5V (hot) from the coolant temperature sensor. If it sees a voltage above 4.5V, it triggers this code.
What a healthy reading looks like
0.5V to 4.5V depending on engine temperature; anything above 4.5V triggers the code.
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 engine coolant temperature sensor connector and wiring for damage or corrosion. Decision: If damaged, repair or replace the wiring. If OK, proceed to step 2.
- 22. Using a multimeter, measure the voltage at the coolant temperature sensor connector with the engine running. Expected: should be between 0.5V and 4.5V. Decision: If out of range, test the sensor; if in range, proceed to step 3.
- 33. If the sensor is out of range, replace the engine coolant temperature sensor. If the sensor checks out, check the ECM for faults.
Common causes
- Short in the coolant temperature sensor circuit
- Faulty coolant temperature sensor
- Bad wiring or connectors in the sensor circuit
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Moderate severity means it's not safe for long distances; performance will be affected.
Will this code come back after clearing it?
If the underlying issue isn't fixed, yes, the code will return.
Why does this code pair with SPN 1100?
SPN 1100 also relates to coolant temperature issues, so they're often seen together.
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