Engine Coolant Temperature Sensor (ECT) 1 Circuit
Fault in the engine coolant temperature sensor 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 engine coolant temperature sensor measures how hot the engine coolant is. If it's broken or there's a wiring issue, the engine doesn't know the correct coolant temperature.
What the computer is actually seeing
The ECU sees the sensor voltage; if it’s out of the expected range (0.5V to 4.5V), it flags a code. A short to ground or open circuit can cause this.
What a healthy reading looks like
The ECT should typically provide a voltage between 0.5V (cold) and 4.5V (hot).
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 connector for corrosion or damage. Are they secure and clean? If not, repair accordingly.
- 2Measure voltage at the ECT connector with the engine running. Is it between 0.5V and 4.5V? If yes, the sensor is likely good. If no, go to the next step.
- 3Test the resistance of the ECT sensor (unplugged, cold engine). It should be around 2.5kΩ at 70°F. Does it match expected values? If yes, check the ECU. If no, replace the ECT sensor.
- 4Check for shorts to ground or open circuits in the wiring harness. Do you find any issues? If yes, repair it. If no, suspect the ECU.
Common causes
- Faulty coolant temperature sensor
- Damaged wiring or connector
- Corrosion at the connector
- ECU malfunction or software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive the vehicle with this code?
Yes, you can drive, but the engine may run poorly or overheat if the sensor is faulty.
Will this code come back after clearing it?
It may return if the underlying issue isn't fixed, especially if the sensor or wiring is faulty.
Why does this code sometimes pair with SPN 1104?
SPN 1104 indicates a similar issue with a different sensor or the same circuit, often pointing to wiring problems.
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