A4 Quattro Wagon L4-2.0L Turbo (CAEB) (2009)
Oxygen Sensor: Testing and Inspection
Oxygen Sensor After Catalytic Converter, Checking
Oxygen Sensor after Catalytic Converter, Checking
Observe all safety precautions: => [ Safety Precautions ] See: Service Precautions/Safety Precautions
View clean working conditions: => [ Clean Working Conditions ] See: Service Precautions/Clean Working Conditions
Prior to repair work, perform a preliminary check to verify the condition. Refer to => [ Preliminary Check ] See: Testing and Inspection/Scan Tool
Testing and Procedures/Preliminary Check.
Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.
For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.
Special tools, testers and auxiliary items required
‹› Generic scan tool
‹› Multimeter
‹› Wiring diagram
Test requirements
‹› The oxygen sensor properly installed
‹› Exhaust system free of leaks
‹› The oxygen sensor fuses OK
‹› Ground connections between engine/transmission/chassis OK
‹› Battery voltage at least 12.5 volts
‹› Coolant temperature at least 80° C
‹› All electrical consumers switched off
‹› Vehicles with automatic transmission, shift selector lever in park or neutral
‹› A/C switched off
‹› Engine running
‹› The oxygen sensor compares the oxygen content of the outside air with the residual oxygen content in the exhaust gas, and generates a voltage
input signal to the engine control module.
‹› If oxygen sensor voltage does not fluctuate, the sensor does not respond, or responds too slowly, the following causes are possible:
‹› Slits in the oxygen sensor tip are plugged
‹› Sensor not up to operating temperature
‹› Sensor has been thermally overloaded
‹› Transition resistance in signal wire or reference ground connection
‹› Sensor has been damaged by electrical contact cleaner or similar contaminant (drawn through signal wire by capillary action due to thermal
fluctuation)
‹› Sensor has been damaged by exposure to silicone. When using silicone sprays and sealants, silicone residue is drawn into the engine where it
passes unburned into the exhaust and can damage the oxygen sensor