Engine Coolant Temperature Sensor Circuit High
The engine coolant temperature sensor is reading a value that is too high.
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 computer is seeing a coolant temperature reading that is higher than the normal range, meaning it might think the engine is overheating.
What the computer is actually seeing
The engine control unit (ECU) expects the coolant temperature to be between 180°F and 220°F (82°C to 104°C) during normal operation.
What a healthy reading looks like
Normal coolant temperature should be between 180°F (82°C) and 220°F (104°C). Values above 220°F (104°C) may trigger this fault. The sensor output voltage should be approximately 0.5V to 4.5V, depending on temperature.
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 in the reservoir and radiator; top off if low or repair any leaks.
- 22. Inspect the wiring and connectors at the coolant temperature sensor for corrosion, damage, or loose connections; repair as needed.
- 33. Use a scan tool to check the live data from the coolant temperature sensor; compare the reading with the actual temperature measured with a thermometer at the coolant neck or radiator.
- 44. If the sensor reading is high but the actual temperature is normal, replace the coolant temperature sensor.
- 55. If the readings match but are high, further diagnose potential overheating issues, like a stuck thermostat, blocked radiator, or failed water pump.
Common causes
- Faulty coolant temperature sensor
- Wiring issues (shorts, opens)
- Bad connector at the sensor
- Coolant leaks or low coolant level
- Engine overheating due to actual mechanical issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to fix it soon. If the engine is genuinely overheating, continued driving can cause severe damage.
Will this code come back after clearing it?
If the issue isn't resolved (like a faulty sensor or wiring problem), it will likely return.
Why does this code pair with SPN 5565?
SPN 5565 indicates low voltage from the coolant temperature sensor, which can occur if there are issues with the sensor or its circuit.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →