Engine Coolant Temperature Sensor 2
The engine coolant temperature sensor 2 is reporting an abnormal reading.
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What it means (plain English)
The engine has multiple temperature sensors; this one is telling the computer the coolant is too hot or too cold, causing potential overheating or poor performance.
What the computer is actually seeing
The engine control unit (ECU) sees a coolant temperature outside of its normal range (like below -40°F or above 300°F) for a specific period of time; typical operation should be around 190°F to 220°F under normal conditions.
What a healthy reading looks like
Expected voltage from the sensor should range from 0.5V (cold) to 4.5V (hot) at 0 to 255 degrees Fahrenheit; outside this range triggers a fault.
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; top off if low, and look for leaks.
- 2Inspect wiring and connectors for damage or corrosion; repair as necessary.
- 3Using a scan tool, check coolant temperature reading versus actual temperature using an infrared thermometer.
- 4If the reading is inaccurate or you find a short circuit, replace the coolant temperature sensor.
Common causes
- Faulty coolant temperature sensor
- Wiring or connector issues (corrosion, breakage)
- Coolant leaks causing incorrect readings
- ECU software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with SPN 240 active?
It's advisable to address it soon; driving could cause overheating.
Will this code come back after clearing?
Yes, if the underlying issue isn't resolved, it will return.
Why does this code pair with SPN 100?
SPN 100 is often referenced because it's related to radiator temperature; issues usually affect both systems.
Working a real vehicle right now?
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