Engine Coolant Temperature (ECT) Sensor
Indicates a problem with the engine coolant temperature sensor or its circuit.
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 coolant temperature sensor measures how hot the engine coolant is. If it's reading wrong, it messes with engine performance and can cause overheating if the computer thinks the engine is colder than it is.
What the computer is actually seeing
The engine control module (ECM) monitors voltage from the ECT sensor, expecting a signal between 0.5V (cold) to 4.5V (hot) depending on the engine temperature.
What a healthy reading looks like
Expected voltage range is 0.5V to 4.5V corresponding to coolant temperatures from -40°C to 125°C (-40°F to 257°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.
- 1Check the coolant level; low coolant can cause false readings.
- 2Inspect the wiring and connector at the ECT sensor for damage or corrosion.
- 3Use a scan tool to monitor the ECT sensor voltage; it should vary with engine temperature.
- 4If the voltage is static and does not change with temperature, replace the coolant temperature sensor.
- 5If the sensor works fine, check for faults in the ECM or wiring harness.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or corrosion in the sensor circuit
- Poor electrical connection or shorts in the harness
- Low coolant level affecting sensor readings
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally safe to drive short distances, but monitor engine temperature closely to avoid overheating.
Will this code come back after I clear it?
If the underlying issue isn't addressed, yes, it likely will.
Why does this code pair with SPN 570?
SPN 570 and SPN 571 relate to the ECT circuit; one is for the sensor itself, while the other could be reading system performance.
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