Checking/removing and installing the temperature sensor (BMW 5 Series E39)

Temperature sensors measure the coolant temperature in the cylinder block, as well as the intake air temperature, and transmit the corresponding signals to the control unit. The sensors contain an element with NTC (Negative Temperature Coefficient), the resistance of which decreases with increasing temperature. If the sensor for measuring the coolant temperature is faulty, the control unit takes the temperature equal to +80°C as a basis; at low ambient temperatures and a cold engine, sensor defects cause difficulties in starting the engine and its uneven operation.

Checking the temperature sensor

Disconnect the plug from the corresponding sensor.

Connect an ohmmeter to the sensor contacts.

Measure the resistance and compare it with the prescribed value. Depending on the temperature, intermediate resistance values are possible. Prescribed values see here.

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

Hang the temperature sensor with a wire and lower it into a bath of water up to the hexagon on the body so that the sensor does not touch the walls of the vessel. First cool the water in the vessel with pieces of ice, and then heat it on a hotplate. Remove the sensor at the specified temperatures and measure its resistance between the contacts. Replace the temperature sensor if necessary.

If the temperature sensor is OK, connect a voltmeter between the sensor plug and ground.

Turn on the ignition. The prescribed voltage value is approximately 5 volts. If there is no voltage, check the conductivity of the wire.



If present, check the ground wire for continuity.

If the wires and temperature sensor are OK, it can be assumed that the control unit is faulty.

Removal the coolant temperature sensor

To avoid drinking the coolant when removing the sensor, you should first partially drain it drain into a suitable container.

Remove the engine cover from the intake manifold and disconnect the hose from the cylinder head cover crankcase ventilation systems.



The coolant temperature sensor is located at the front of the engine cylinder block under the strelka intake manifold.

Disconnect the plug and unscrew the temperature sensor. The signals from the sensor are transmitted to the DME control unit and the indicator on the instrument cluster.

Installation

Screw in the temperature sensor with a new gasket and tighten it to a torque of 20 Nm.

Connect the plug and secure it with a wire clamp.

Connect the crankcase ventilation hose to the cylinder head cover and secure it, install the engine cover.

Top up the coolant level and remove air from the cooling system.

Perform a test drive and check the temperature sensor connection point for leaks; if necessary, tighten the sensor slightly.



Read the contents of the DME system fault code memory. After troubleshooting, erase the contents of the memory.

Removal the intake air temperature sensor

Unscrew the fastening throttle valve pipe.

Caution: Do not disconnect the throttle linkage or throttle body heating system hoses.

Press the locking button "arrow" on the sensor and pull it out of the intake manifold with a downward movement. Disconnect the plug from the sensor.

Installation

Secure the sensor to the intake manifold.

Connect the plug and secure it with a wire clamp.

Install the throttle body pipe.

Put on the air intake hose and secure with a clamp.

Read the contents of the DME system fault code memory. After troubleshooting, erase the contents of the memory.

[The text is based on materials from the website: BMWMAN.ru]