Engine Coolant Temperature Sensor 1
Indicates an issue with the engine coolant temperature sensor 1.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine coolant temperature sensor measures how hot the coolant is. If it's faulty, the engine may run too hot or too cold, affecting performance and emissions.
What the computer is actually seeing
The ECM monitors the resistance of the coolant temperature sensor. An open circuit or incorrect resistance values will trigger this fault.
What a healthy reading looks like
Coolant temperature should typically range between 185°F and 220°F (85°C to 104°C). Resistance should be around 20-30 kΩ at 68°F (20°C).
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 engine coolant level; fill if low and recheck the code.
- 22. Inspect the wiring and connector at the coolant temperature sensor for damage or corrosion; repair as needed.
- 33. Measure the resistance of the coolant temperature sensor with a multimeter at known temperatures. Compare it to expected values.
- 44. If the resistance is outside expected range, replace the coolant temperature sensor. Recheck for code.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or damaged connectors
- Coolant leaks affecting the sensor
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It may be driveable, but performance could be affected and emissions may increase.
Will this code come back after clearing?
If the underlying issue isn't fixed, yes, it will return.
Why does this code also show up with SPN 1009?
SPN 1009 is related to the same cooling system, indicating a possible compound issue.
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