Engine Coolant Temperature Sensor 1
The Engine Coolant Temperature Sensor 1 is signaling an out-of-range value.
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What it means (plain English)
The engine's computer gets temperature readings from the coolant temperature sensor, which tells it how hot the engine is running. If the sensor reads way too high or too low, it can cause performance issues because the computer can't manage the engine properly.
What the computer is actually seeing
The engine control module (ECM) is getting an unexpected voltage range from the engine coolant temperature sensor, typically outside 0.5 to 4.5 volts, indicating a potential open circuit or short to ground.
What a healthy reading looks like
Normal operating voltage from the coolant temperature sensor should range between 0.5V (around -40°C or -40°F) and 4.5V (around 125°C or 257°F).
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 for the coolant temperature sensor for any damage or corrosion. If found, repair or replace as needed.
- 22. With the engine at operating temperature, test the voltage output from the coolant temperature sensor. It should be between 0.5V to 4.5V. If not, replace the sensor.
- 33. Inspect the engine coolant level. Low coolant can cause an incorrect reading. Refill if necessary and re-test.
- 44. Scan for other related codes. If additional codes are present, resolve those issues before returning to this one.
Common causes
- Faulty engine coolant temperature sensor
- Damaged wiring or connectors to the sensor
- Coolant leaks affecting sensor readings
- ECM software issues
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with code SPN 1175?
It's moderate severity; it can impact drivability and emissions, so fix it soon.
Will this code come back after clearing it?
If the underlying issue isn't fixed, yes, it will return.
Why do I see this code with others like SPN 1213?
These codes can stem from related issues such as temperature readings affecting performance, leading to multiple codes being set.
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