Air Quality Sensor -G238- /Humidity Sensor In Fresh Air Intake Duct -G657-, REMOVING AND INSTALLING

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NOTE:

Different versions depending on the vehicle date of manufacture and A/C system version ("Basis" or "Convenience"). Refer to Air Quality Sensor -G238-, FUNCTION .

The Air Quality Sensor -G238- is only installed on vehicles with the "Convenience" A/C system.

The Humidity Sensor in Fresh Air intake Duct -G657- is only installed on vehicles from MY 2012 as a running change. Refer to Air Quality Sensor -G238-, FUNCTION .

The Air Quality Sensor -G263- /Humidity Sensor in Fresh Air intake Duct -G657- are highly sensitive electronic components that can get damaged if they come in direct contact with solvents, fuels or chemicals (for example, impurities may enter through area -A-). Therefore, never install an Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- that was stored, for example, in a tool box.

Fig 1: Identifying Air Quality Sensor G238

Courtesy of AUDI OF AMERICA, LLC

Following removal, do not set down the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- in areas where it could come into contact with solvents, fuels or certain chemical compounds (liquids or vapors).

There are different versions of the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- with different functions, therefore pay attention to the correct version .

On vehicles with a high voltage system (hybrid vehicles)

Observe all of the additional warnings for all work performed on vehicles with the high voltage system. Refer to HIGH VOLTAGE VEHICLES SAFETY PRECAUTIONS and HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

If it is necessary for the following procedure to perform work near high voltage components, "perform a visual inspection of the high voltage components and cables for damages" (refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES ) and "always follow the warnings when working on the high voltage system". Refer to HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

WARNING:

Risk of unintended engine start

The ignition must be turned off and the ignition key must remain outside of the vehicle when working on vehicles with a high voltage system.

WARNING:

Handling high voltage cables:

Do not stand on or place tools on high voltage cables and their components as it may damage the cable insulation.
Never bend or kink high voltage cables forcefully as it may damage the cable insulation.
The round high voltage connectors are color coded with an external color ring and are mechanically coded using the guide- or code tabs. Always make certain that the coding matches when connecting the round connector in order to avoid any mechanical damage the high voltage connector.

CAUTION:

There is a risk of electrocution from damaged high voltage components.

Observe the following when working around high voltage components and high voltage wires:

Never work around high voltage components and cables with cutting, deformed, or sharp edged tools, or heat sources such as welding or soldering tools, heated air, and thermal glue.
Inspect the high voltage components visually before beginning.
Perform a visual inspection of the Electric Drive Power and Control Electronics -JX1-, the Electro-Drive Drive Motor -V141-, the Electrical A/C Compressor -V470- and the high voltage lines when working in the engine compartment.
Perform a visual inspection of the high voltage lines and covers when working on the underbody.
Perform a visual inspection of the high voltage lines and the Electrobox with the High Voltage System Maintenance Connector -TW- when working in the luggage compartment.
Perform a visual inspection on all of the potential equalization cables.

Observe the following items when performing the visual inspection:

The components do not display any signs of external damage.
The high voltage cable insulation and the potential equalization cables are not damaged.
The high voltage cables do not display any abnormal deformations.
Every high voltage component is marked with a red warning label.

-- Turn off the ignition.

-- Remove the rubber seal -A- and plenum chamber cover -B- (different versions). Refer to PLENUM CHAMBER COVER, REMOVING AND INSTALLING .

Fig 2: Identifying Plenum Chamber Cover And High Voltage Components

Courtesy of AUDI OF AMERICA, LLC

Visually inspect the high voltage components -D- (here the Electric Drive Power and Control Electronics -JX1-) and the high voltage cables -E- after removing the plenum chamber cover -B-. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

Be careful not to damage any high voltage components -D- or the high voltage cables -E-. Refer to HIGH VOLTAGE SYSTEM GENERAL WARNINGS .
Visually inspect the high voltage components -D- and high voltage cables -E- after completing the work procedures and before installing the plenum chamber cover -B-. Refer to HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

For vehicles without a high voltage system

-- Switch off ignition.

-- Pull off the rubber seal -B- on the left side as far as necessary. Refer to PLENUM CHAMBER COVER, REMOVING AND INSTALLING .

Fig 3: Identifying Fresh Air Intake Cover -A-, Rubber Seal -B- And Wiper Arm

Courtesy of AUDI OF AMERICA, LLC

-- Remove the cover for the fresh air intake on the cowl panel trim -A- or the cowl panel trim (different versions). Refer to PLENUM CHAMBER COVER, REMOVING AND INSTALLING .

NOTE:

If necessary, carefully loosen the cowl panel trim from the retainer on the windshield cross member -C-. Refer to PLENUM CHAMBER COVER, REMOVING AND INSTALLING .

All vehicles

-- Rotate the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- -A- approximately 90° to the left and remove it from the fresh air intake -C-.

Fig 4: Removing Air Quality Sensor

Courtesy of AUDI OF AMERICA, LLC

-- Remove the connector -B- from the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657-.

Terminal assignment in connector -B-

1 -

B+ (terminal "15")

2 -

Ground (terminal "31")

3 -

Signal wire to the Vehicle Electrical System Control Module -J519-, refer to appropriate SYSTEM WIRING DIAGRAM.

NOTE:

The signal from the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- cannot be evaluated by workshop equipment.

The Vehicle Electrical System Control Module -J519- evaluates the data from the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- and then transmits it to the Climatronic Control Module -J255- display and control head via the Data Bus.

There are different versions of the air intake shroud for the fresh air intake -C- (with and without a mount for the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- -A-, front mount or on the side). To ensure the correct version .

The measured values for the Air Quality Sensor -G238- /Humidity Sensor in Fresh Air intake Duct -G657- are displayed in the measured value block for the Climatronic Control Module -J255- display and control head and in the measured value block for the Vehicle Electrical System Control Module -J519-. For the explanatory notes of the displays using the Vehicle Diagnostic Tester in the "Guided Fault Finding " function