Engine Coolant Temperature Sensor 1
The engine coolant temperature sensor is out of range.
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 reading the coolant temperature sensor data as too high or low, affecting engine performance.
What the computer is actually seeing
The ECM expects the coolant temperature to be between 190°F and 220°F (88°C to 105°C) during normal operation.
What a healthy reading looks like
Normal operating range is between 190°F (88°C) and 220°F (105°C). Outside of this range signals a fault.
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 coolant level; ensure it's within the acceptable range.
- 22. Inspect the wiring and connectors at the coolant temperature sensor for damage or corrosion.
- 33. Use a multimeter to test the coolant temperature sensor output; it should vary between 0.5V (0°C) to 4.5V (100°C).
- 44. If sensor readings are stable but out of range, replace the coolant temperature sensor; then recheck.
- 55. If readings fluctuate wildly, check the wiring harness for shorts or opens.
- 66. If all checks out and the code persists, consider inspecting the engine coolant thermostat.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issue or corrosion in the connector
- Coolant leak affecting temperature readings
- Faulty engine coolant thermostat
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Moderate severity means you should fix it soon; drivability may be affected.
Will this code come back after I clear it?
If the underlying issue isn't resolved, it will likely return.
Why might this code be paired with SPN 172?
SPN 172 and SPN 180 both relate to coolant temperature sensing; if one fails, the other might too.
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 →