Checking, removing and installing the coolant temperature sensor (Opel Vectra A)

This sensor measures the temperature of the coolant and transmits information about it to the computer. The sensor has a thermoelement that decreases its resistance as the temperature increases. When a certain lower temperature limit is reached, the computer registers code 14, and when a certain upper limit is reached, code 15. The computer perceives the latter code as a coolant temperature of 80°C. This temperature corresponds to a warmed-up engine.

Examination

Disconnect the connector from the sensor.

Connect an ohmmeter to the sensor contacts.



Measure the resistance and compare it with one of the above values.

If the resistance does not correspond to the specified value, remove the sensor.

Hang the sensor on a wire in a container with water so that it does not touch the walls of the container. Cool the water with ice, and then heat it on the stove. Remove the sensor at the temperatures specified in the table above and measure its resistance. Replace the sensor if necessary.

If the sensor is in good condition, connect a voltmeter to the sensor contact and ground (in the Multec system, connect contact B of the diagnostic connector to ground).



Turn on the ignition. The voltmeter should show 5.1 V. If there is no voltage, check the connections.

If the wires and sensor are OK, then the problem is in the computer.

Removal

Attention! To prevent coolant leakage when replacing the sensor, it is necessary to first drain some of the liquid into a suitable container.

Multec System

Motronic and Ecotronic systems

Disconnect the connector (see fig.).

Unscrew the sensor.

Installation

Screw the sensor into place with a new sealing ring and tighten it to a torque of 10 Nm.

Caution! Do not exceed the sensor tightening torque!

Connect the connector.

Fill with coolant.

Bleed air from the cooling system.

Take a test drive and check the tightness of the connections. Tighten the sensor if necessary.