Engine Coolant Temperature Sensor Performance
The engine coolant temperature sensor is providing a signal outside of expected range.
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What it means (plain English)
The engine's computer is reading that the coolant temperature sensor is either malfunctioning or giving incorrect temperature readings that don't match what the engine is experiencing.
What the computer is actually seeing
The engine control module expects the coolant temperature to be between 180°F and 220°F (82°C - 105°C) while running. If it senses values below 140°F (60°C) or above 240°F (115°C) continuously, it sets this code.
What a healthy reading looks like
Coolant temperature during normal operation should be between 180°F and 220°F (82°C - 105°C).
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.
- 11. Check the coolant level. Ensure it is within the normal range; refill if necessary.
- 22. Inspect the wiring and connectors to the coolant temperature sensor for damage or corrosion. Repair as needed.
- 33. Use a scan tool to monitor the actual coolant temperature vs. the sensor reading. Are they close?
- 44. If readings are above/below expected values, disconnect the sensor and measure resistance. Should be approximately 2000 ohms at 70°F (21°C). If it’s significantly off, replace the sensor.
- 55. Test the vehicle's thermostat operation. Start the engine and allow it to reach operating temperature. It should open around 195°F (91°C). If not, replace the thermostat.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or loose connectors
- Low coolant level
- Thermostat stuck open
- ECM calibration issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally safe to drive, but you may see overheating or poor performance, so fix it soon.
Will this code come back after clearing?
Yes, if the underlying issue isn't resolved, it will reappear.
Why does this code sometimes pair with SPN 301?
SPN 301 is related to the coolant temperature sensor voltage, which can also be impacted if the sensor itself is faulty.
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