FMI 7 - Engine Coolant Temperature Sensor 1 - Voltage Above Normal, Or Shorted To High Source
Engine coolant temperature (ECT) sensor reading is too high or has a short circuit to the power supply.
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What it means (plain English)
The coolant temperature sensor is reading a higher voltage than what is normal, indicating either it's bad or there's a wiring issue giving false readings.
What the computer is actually seeing
The engine control unit (ECU) expects the ECT sensor to give readings typically between 0.5V (cold) to approximately 4.5V (hot). Anything significantly above that can trigger this code.
What a healthy reading looks like
Normal voltage outputs for ECT sensor are between 0.5V to 4.5V depending on temperature. Check manufacturer specs for exact values.
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 coolant level; it should be between the min and max marks. If it's low, refill and retest.
- 2Inspect the ECT sensor connector for damage or corrosion. Repair as needed before proceeding.
- 3Using a multimeter, measure the voltage at the ECT sensor connector with the key on, engine off. It should match expected values (0.5V - 4.5V). If it's higher than expected, suspect a wiring issue.
- 4Ohm the ECT sensor. Compare resistance to temperature values in manufacturer service data. If resistance does not match, replace the sensor.
- 5If the sensor checks out, inspect the wiring harness leading to the sensor for any shorts or breaks. Fix as necessary.
Common causes
- Faulty ECT sensor
- Wiring harness short to power
- Corroded or damaged connectors
- Coolant leaks affecting sensor operation
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Moderate severity means you can drive but should fix it soon; overheating can occur.
Will this issue come back after fixing?
If wiring is repaired but underlying causes are not addressed, it might return.
Why do I see this code with other codes?
This code often pairs with other ECT or cooling system-related codes due to related components failing.
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