Engine Coolant Temperature Sensor 1 Voltage Out of Range
The ECM detected an invalid signal from the coolant temperature sensor.
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 computer is reading the engine coolant temperature sensor as having a voltage that doesn't match expected values, indicating it's either too high or too low.
What the computer is actually seeing
The ECM expects a coolant temperature sensor voltage between 0.5V (for -40°C, -40°F) and 4.5V (for 150°C, 302°F). If the voltage is outside this range, like 0V or above 4.5V, it triggers a fault.
What a healthy reading looks like
Coolant temperature sensor should typically output between 0.5V (around -40°C) and 4.5V (about 150°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.
- 1Check the engine coolant level first; if low, refill and retest.
- 2Inspect the wiring and connector for the coolant temperature sensor for damage or corrosion.
- 3Disconnect the sensor and check the resistance values across the terminals; it should change with temperature (about 2.5k ohm at 25°C).
- 4Reconnect the sensor and measure the voltage signal at the ECM connector; it should be within 0.5V to 4.5V. If it’s not, replace the sensor.
Common causes
- Faulty coolant temperature sensor
- Shorted wiring or ground problems
- Open circuit in the sensor line
- ECM software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Driving with this code can lead to overheating and potential engine damage, so fix it soon.
Will this code come back after I clear it?
If the underlying issue isn't resolved, yes, you can expect it to return.
Why does this code pair with other codes?
Codes can relate to shared systems like coolant temperature and engine performance metrics.
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