Engine Cooling Temperature Sensor 1 Failure
The Engine Cooling Temperature Sensor 1 has malfunctioned.
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 computer is losing data from the coolant temperature sensor. This can happen when the sensor goes bad or there’s an issue with the wiring to it.
What the computer is actually seeing
The engine control unit expects a variable voltage signal from the coolant temperature sensor, reflecting the engine coolant temperature. A failure might show as a constant voltage or out-of-range values.
What a healthy reading looks like
Typically, the voltage should range from 0.5V (very cold) to 4.5V (very hot) depending on the temperature, showing around 1.5V at 180°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 for any visible wiring damage or corrosion near the coolant temperature sensor.
- 22. Inspect the sensor connector for bent pins or signs of water intrusion; repair as needed.
- 33. Measure the resistance of the coolant temperature sensor; it should have a specific resistance based on the temperature (approx. 2.5k ohms at 180°F). If out of specs, replace the sensor.
- 44. With the key on, but engine off, check the voltage at the sensor connector; it should be around 5V. If not, check the wiring back to the ECU.
- 55. If the sensor and wiring check out but the code persists, consider checking ECU programming or software updates.
Common causes
- Faulty coolant temperature sensor
- Wiring or connector issues (corrosion or broken wires)
- Coolant leaks affecting sensor operation
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive with this code?
Yes, but it's best to fix it soon to prevent engine overheating.
Will this code come back after clearing?
It may come back if the underlying issue isn't resolved.
Why does this code pair with SPN 761?
SPN 761 also relates to coolant temperature but might indicate a different sensor or error in the system.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →