Engine Coolant Temperature Sensor Circuit Low
Engine coolant temperature sensor is reporting low voltage.
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What it means (plain English)
The coolant temperature sensor is telling the engine computer that the engine is cooler than it really is, which can affect how the engine runs.
What the computer is actually seeing
The engine control unit (ECU) expects the coolant temperature signal to be between 0.5V and 4.5V while the engine is running, correlating to temperatures from -40°C to 125°C. When the sensor voltage drops below 0.5V, it triggers this fault code.
What a healthy reading looks like
Expect the coolant temperature sensor to produce a voltage between 0.5V and 4.5V for temperatures ranging from -40°C to 125°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.
- 1Check the coolant level and top off if needed. If low, address the leak before further diagnosis.
- 2Inspect the wiring and connectors at the coolant temperature sensor for signs of damage or corrosion. Repair as needed.
- 3Use a multimeter to measure the voltage at the coolant temperature sensor connector with the engine running. Voltage should be between 0.5V and 4.5V. If it's lower than 0.5V, replace the sensor.
- 4If the sensor voltage is normal, check the ECM for any software updates or faults in other related sensors.
Common causes
- Faulty coolant temperature sensor
- Wiring or connector issue in the sensor circuit
- Low coolant level
- ECU software issue
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's usually drivable but expect potential performance issues; fix soon to avoid further complications.
Will this code come back after repair?
If the sensor and circuit are correctly fixed, it should not return. Monitor the system after repairs.
Why do I see this code with SPN 110?
Both codes can relate to temperature sensor issues; SPN 110 often refers to a different sensor that might have simultaneous failures.
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