Engine Coolant Temperature Sensor Signal

The engine coolant temperature sensor measures how hot the engine coolant is. If this sensor sends a value that's way too high or low, it confuses the engine's computer, affecting fuel delivery and potentially causing overheating.

The ECU expects the engine coolant temperature to range between 175°F and 225°F (about 80°C to 107°C). If it receives a signal outside this range, like 50°F or 300°F, it triggers this code.

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.

1. 11. Check the engine coolant level. If low, top it off and see if the code returns after a test drive. Decision: If the code returns, proceed to step 2; if not, problem resolved.
2. 22. Inspect the wiring and connector of the coolant temperature sensor. Look for damage, corrosion, or loose connections. Decision: If you find issues, repair them and see if the code comes back; if not, problem resolved. If wiring looks good, move to step 3.
3. 33. Use a scan tool to monitor the live data from the coolant temperature sensor. Check its readings against the expected values while the engine warms up. Decision: If the readings are outside of the expected values, replace the coolant temperature sensor; if they are normal, check the ECU.

• Faulty engine coolant temperature sensor
• Wiring issues or corroded connectors
• Low coolant level
• ECU malfunction

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