General information
The coolant temperature sensor is installed in the channel of the cylinder head cooling jacket. It detects the temperature of the engine coolant and transmits a signal to the electronic engine control unit. The sensor is a thermistor sensitive to temperature changes. The resistance of the sensor decreases as the temperature of the engine coolant increases.
Based on the voltage of the sensor signal, the electronic engine control unit estimates the temperature of the coolant and corrects the duration of the injector opening signal and the ignition timing. If the coolant temperature is very low, then the electronic engine control unit enriches the air-fuel mixture (increases the duration of the injector opening signal) and increase the ignition timing (sets early ignition).
2.0L/2.4L engines | 2.7L engine |
Troubleshooting Guide
If the idle speed is abnormal when warming up a cold engine, or the warming up of the engine is accompanied by black smoke from the exhaust pipe, then the coolant temperature sensor may most likely be the cause.
Sensor test
1. Remove the coolant temperature sensor from the engine intake manifold.
2. Immerse the measuring part of the sensor in water at a known temperature and measure the resistance between the sensor leads.
Table. Rated values.
Temperature | Resistance (kOhm) |
0°C | 5,9 |
20°C | 2,5 |
40°С | 1,1 |
80°С | 0,3 |
3. If the measured resistance differs from nominal values replace the gauge of temperature of a cooling liquid.
Testing with a tester
1. Conditions for the audit.
Ignition key: in position "ON" (ON) or the engine is running.
2. Performing a check:
Read tester readings (coolant temperature recorded by the sensor).
Table. Rated values.
Engine condition (coolant temperature) | Rated value |
At -20°С | -20°С |
At 0°C | 0°C |
At 20°C | 20°C |
At 40°C | 40°С |
At 80°C | 80°С |
Checking with a voltmeter
Measure the signal voltage of the coolant temperature sensor.
Table. Rated values.
Engine condition (coolant temperature) | Rated value |
At 0°C | 4.05V |
At 20°C | 3.44 V |
At 40°C | 2.72 V |
At 80°C | 1.25V |