Removal and installation, checking of temperature sensor (BMW 5 Series E34)

The temperature sensor measures the engine temperature and transmits this information to the control unit. The temperature sensor contains an NTC element (NTC = negative temperature coefficient), the resistance of which decreases with increasing temperature. If the sensor fails, the control unit assumes the temperature value is +80°C. This corresponds to the temperature of a warmed-up engine, and at low outside temperatures and a cold engine, starting the engine is difficult and its operation is uneven.

Examination

Disconnect the connector.

Connect an ohmmeter to both contacts of the connector.

Measure the resistance and compare with the specified value. Intermediate values are possible at different temperatures. For specified values, see the table below.

If the result differs from the specified value, remove the sensor.

Place the sensor on a wire hook in a water bath so that it does not touch the walls of the vessel. Cool the water with ice cubes, and then warm it up on a hotplate. At the specified temperatures, remove the sensor and measure the resistance between its contacts.

If the temperature sensor is normal, connect the voltmeter to the connector contacts and ground.

Turn on the ignition. The specified value is about 5 volts. If there is no voltage, ring the wire.

Ring the ground wire.

If the sensor and wires are normal, the control unit is defective.

Removal

Note: To prevent coolant from leaking out when removing the sensor, drain some of the coolant into a container.

Remove the temperature sensor connector.



Unscrew the temperature sensor 2 OME.

1 - coolant temperature sensor for the gauge on the instrument panel.

Installation

Install the temperature sensor with a new gasket and tighten to a torque of 12-14 Nm (diesel engine: 18+1 Nm).

Caution: Do not overtighten the temperature sensor.

Connect the connector:

Connector - Sensor

• Blue - DME temperatures;
• Black - coolant temperature for the gauge on the instrument panel.

Fill with coolant.

Remove air from the cooling system.

Perform a test drive and check the tightness of the temperature sensor installation location; tighten it a little if necessary.