Engine Coolant Temperature Sensor Circuit Low

The engine coolant temperature sensor measures how hot the coolant is. If the sensor reports a low voltage (usually under 0.5 volts), it thinks the engine is cooler than it really is, which can cause performance issues.

The engine control unit (ECU) expects a voltage from the sensor typically between 0.5 to 5 volts, depending on the temperature. If it sees a voltage under 0.5 volts, 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 coolant level in the radiator and reservoir; top off if low. If coolant is low, fix the leak and retest. Decide: Low coolant? Fix and retest.
2. 22. Inspect the wiring and connectors for the coolant temperature sensor for damage, corrosion, or looseness. Repair any issues found. Decide: Wiring okay? Go to step 3.
3. 33. With the engine running, use a multimeter to check the voltage at the sensor connector. You should see a voltage between 0.5 to 5.0 volts. If reading is low, replace the coolant temperature sensor. Decide: Voltage acceptable? Repair or replace the sensor as needed.

• Faulty engine coolant temperature sensor
• Open or shorted wires in the sensor circuit
• Corroded or loose connections at the sensor
• Low coolant level affecting sensor reading

$$ - $$$