Engine Coolant Temperature (ECT) Sensor Voltage
Indicates a problem with the engine coolant temperature sensor signal.
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What it means (plain English)
The ECM is getting a voltage reading from the coolant temperature sensor that isn't within the range it's expecting, which usually means the sensor is bad or there's a wiring issue.
What the computer is actually seeing
The Engine Control Module (ECM) sees voltage readings from the ECT sensor that are either too high (usually above 4.5V) or too low (below 0.1V).
What a healthy reading looks like
Expected voltage from the ECT sensor is typically between 0.1V and 4.5V, depending on coolant temperature.
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 wiring and connectors of the ECT sensor for damage or corrosion. Look for loose connections.
- 2Using a multimeter, measure the voltage at the ECT sensor connector. It should read between 0.1V and 4.5V depending on the engine temperature.
- 3If the voltage is out of range, inspect the wiring for shorts or opens and repair as needed.
- 4If wiring is fine, replace the engine coolant temperature sensor and retest.
- 5If the problem persists after replacing the sensor, consider checking for ECM updates or potential issues with the ECM itself.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issues (shorts or opens)
- Corroded or loose connectors
- ECM software issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive with this code as it can lead to overheating or poor engine performance.
Will the code come back after clearing?
It can come back if the underlying issue isn't fixed, particularly a faulty sensor or wiring issue.
What happens if I ignore this error?
Ignoring this error can lead to engine overheating and potentially serious engine damage.
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