A3 L4-2.0L Turbo (BPY) (2006)
Climate Control Exhaust Gas Sensor: Testing and Inspection
Air Quality Sensor G238, Checking
Special tools, testers and auxiliary items required
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Diagnostic operation system VAS 5051 A with diagnostic cable VAS 5051/5A
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Test gas "D 007 855 A2" Parts Catalog
Test requirements
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Vehicle is in area where there is clean recirculating air (not near running engines, openings from exhaust systems, etc.)
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Engine compartment and plenum chamber are clean (not contaminated with oil and/or fuel).
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The engine compartment and plenum chamber were not sprayed with cleaning or preservative solutions.
Checking
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With ignition switched off, connect Diagnostic Operation System VAS 5051 A with Diagnostic Cable - 3 Meter VAS 5051/5A to the 16-pin Data
Link Connector (DLC) of vehicle. See: Heating and Air Conditioning/Testing and Inspection/Scan Tool Testing and Procedures/Diagnostic
Operation System VAS 5051 A, Connecting and Selecting Functions and Vehicle Diagnosis, Testing and Information System VAS 5051 in the
"Guided Fault Finding" function.
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Start engine.
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Check DTC memory of A/C control head Climatronic Control Module J255 Vehicle Diagnosis, Testing and Information System VAS 5051 in
"Guided Fault Finding" function.
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Set operating mode "Auto" on A/C control head Climatronic Control Module J255.
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Switch on "automatic air recirculation" function on A/C control head Climatronic Control Module J255.
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Wait 30 seconds (warm up time for Air Quality Sensor G238).
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Select the "Read measuring value block" function of diagnostic operation system VAS 5051 A (Read measuring value block, display group "014"
and Vehicle Diagnosis, Testing and Information System VAS 5051 in the "Guided Fault Finding" function). See: Heating and Air
Conditioning/Testing and Inspection/Scan Tool Testing and Procedures/Measuring Value Blocks (Function 08)/A/C System, Initiating Read
Measuring Value Block Function
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Read indications shown in display fields "3" and "4".
NOTE:
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Display field "4" shows the operating condition of fresh/recirculating air flap and display field "3" shows the condition of the Air Quality
Sensor G238 signal. (Explanatory notes of possible displays, See: Heating and Air Conditioning/Testing and Inspection/Scan Tool Testing and
Procedures/Measuring Value Blocks (Function 08)/A/C System, Initiating Read Measuring Value Block Function Read Measuring Value
Block and Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.)
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Specified value in display field "4" (no request for "recirculating air mode" present, A/C system in fresh air mode)
or
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Specified value in display field "4" ("partial recirculating air mode", fresh /recirculating air flap in approximate center position)
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Place spray head -A- of test gas bottle over air inlet of air quality sensor -B-.
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Press spray head -C- of test gas bottle for 1 second.
NOTE:
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Air Quality Sensor G238 is available in different housings, but functionally they are the same Parts Catalog.
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The content of the test bottle consists of pure oxygen with a specified amount of nitrogen oxide.
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If cigarette smoke or cigarette lighter gas (gas is heavier than air, therefore remove Air Quality Sensor G238 and turn it around) impinges the
sensor, it also reacts.
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Read indication in display field "4".
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Specified value: (request for "Automatic air recirculation" present, request is fulfilled, A/C switches to recirculating air mode)
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Wait a short period time (approximately 1 minute, depending on amount of test gas sprayed on Air Quality Sensor G238).