Engine Coolant Temperature Sensor Circuit Low
Indicates a low signal from the engine coolant temperature sensor.
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What it means (plain English)
The engine's computer is seeing a temperature reading from the coolant sensor that is much lower than expected, which can lead to incorrect engine monitoring and performance issues.
What the computer is actually seeing
The Engine Control Module (ECM) is monitoring the coolant temperature sensor signal. A normal range for this signal is typically between 0.5V (at around -40°C) to 4.5V (around 150°C). A voltage reading below 0.2V is a low signal indicating a problem.
What a healthy reading looks like
0.5V to 4.5V under normal operational conditions.
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 the coolant level; it should be at the full mark.
- 2Inspect wiring and connectors to the coolant temperature sensor for damage or corrosion.
- 3Measure the voltage at the coolant temperature sensor connector, it should be between 0.5V and 4.5V. If it's below 0.2V, go to the next step.
- 4Disconnect the sensor and check the resistance; it should change with temperature per manufacturer specifications. If it doesn't, replace the sensor.
- 5If the sensor is good, check the wiring continuity back to the ECM.
Common causes
- Faulty coolant temperature sensor
- Wiring issue or short circuit
- Corroded connector or bad ground
- Low coolant level
- ECM failure
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive the vehicle with this code present?
Yes, but the engine may not reach optimal performance and you could overheat the engine without proper temp readings.
Will this code come back after clearing it?
Yes, if the underlying issue is not fixed, it will reappear.
Why does this code sometimes appear with other codes?
Multiple faults may arise from related issues, such as wiring problems affecting the sensor and other components.
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