A4 Quattro Sedan L4-2.0L Turbo (CAEB) (2009)
Oxygen Sensor: Testing and Inspection
Heated Oxygen Sensor HO2S, Checking
Heated Oxygen Sensor HO2S, Checking
Observe all safety precautions: => [ Safety Precautions ] See: Computers and Control Systems/Service Precautions/Safety Precautions
View clean working conditions: => [ Clean Working Conditions ] See: Computers and Control Systems/Service Precautions/Clean Working
Conditions
For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.
‹› Use only gold-plated terminals when servicing terminals in the electrical harness connector of the Heated Oxygen Sensor (HO2S) (G39 ).
Special tools, testers and auxiliary items required
‹› multimeter.
‹› Wiring diagram.
Test requirements
‹› The Heated Oxygen Sensor (HO2S) (G39) fuse OK.
‹› The Oxygen Sensor (O2S) Heater (Z19) before catalytic converter OK. Refer to=> [ Oxygen Sensor O2S Heater, Checking ].
‹› Battery voltage at least 12.5 volts.
‹› All electrical consumers such as, lights and rear window defroster, switched off.
‹› A/C switched off.
‹› Ground (GND) connections between engine/transmission/chassis OK.
‹› Exhaust system between catalytic converter and cylinder head properly sealed.
‹› Coolant Temperature at least 80 °C.
Test procedure
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Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] See: Computers and Control Systems/Testing
and Inspection/Scan Tool Testing and Procedures/Preliminary Check
Start diagnosis
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Connect scan tool.