Logic of naming sensors in VW-group is simple it contains "G" (german "Geber") + sensor number. The sensor number is unique. Here you can find fitting location, connectors and pins description, some information about sensors signals.

To our mind, sensors information is reference, so there is only simple search by sensor number.


Audi A8 4E (2002 -)
Audi A6 4F (2005- )
Audi A4 8K (2008-)
Audi Q5 8R (2009- )

Audi A8 4E (2002 -). G191 Описание

Centre vent temperature sender -G191


See Fitting Location, Fig.: A87-0548

A Connector of temperature sensor -G191

B Centre vent temperature sender -G191


The air conditioner is regulated within an overall temperature range between 18°C and 28°C. However, the possibilities of individual climate settings for each selectable position must be set against the fact that the climate zones are not physically separated from each other.

In the selected automatic function the air conditioner uses the sensors to determine how much the air for the climate zone concerned needs to be heated or cooled in order to deliver the selected temperature.

In this, the air conditioner control unit determines the flow rate of the engine coolant in the heating circuit through the heat exchangers or the cooling power of the refrigerant circuit, as appropriate. The air conditioner control unit decides according to the requirement, for example that the regulated warm or cooled air for ventilation is routed to the "driver" and "front passenger" climate zone and, with the (optional) 4-zone air conditioner, to the left and right rear passengers.

The design layout with two adjacent heat exchangers provides a right/left split of the passenger compartment ventilation.

The temperature of these two air flows for the left and right halves of the vehicle is primarily determined by the temperature setting at the front seat positions.

The centre vent temperature sender -G191 is located in the centre air outlet duct in the air distribution housing in the middle of the dash panel at the front.

The air flowing out of the right and left side air ducts from the heater/air conditioner unit through the heat exchangers is mixed in the air distribution housing in the middle of the dash panel and recorded with the temperature-sensitive resistor and so is available as an influencing variable in the temperature monitoring and control function of the operating and display unit -J255. Depending on the flap setting, the air is routed to the two centre vents for direct ventilation and to the vents in the top of the dash panel for indirect ventilation. The temperature sender -G191 is designed as an NTC sensor. The resistance is evaluated as a signal from the control unit and regulates the air temperature to the centre left and right vents.


K Notes:

J As the temperature falls the electrical resistance increases.

J If the fault: "short to earth" is detected by the operating and display unit -J255, the value 150°C is entered in display zone 3 of measured value block 017.

J If the fault: "open circuit/short to positive" is detected by the operating and display unit -J255, the value -70°C is entered in display zone 3 of measured value block 017.

J If the centre vent temperature sender -G191 fails, operation is maintained.

J Experience shows that temperature senders are the most frequent cause of temperature control faults. They do not usually fail immediately, but deliver false values to the control unit based on an additional wire resistance as a result of damage or corrosion in the connector contacts. Thus a comparison with the values of senders -G150 and -G151 in the relevant display zones is recommended for optimum diagnosis.

J A Air conditioner; Rep.Gr. 87; Removing and installing centre vent temperature sender -G191

J A Current flow diagram; ELSA


Measured value block 017


Display zone 1:


Readout of left vent temperature sender -G150 in °C


Display zone 2:


Readout of right vent temperature sender -G151 in °C


Display zone 3:


Readout of centre vent temperature sender -G191 in °C


Display zone 4:


Display zone currently not used

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