A8L Quattro Sedan W12-6.0L (BSB) (2005)
Oxygen Sensor: Testing and Inspection
Oxygen Sensors and Oxygen Sensor Regulation Before Catalytic Converter, Checking
Diagnostic Procedures
Oxygen Sensors and Oxygen Sensor Regulation Before Catalytic Converter, Checking
‹› When servicing terminals in harness connector of oxygen sensors, use only gold-plated terminals.
‹› The oxygen sensors before catalytic converter have a constant regulation and can be differentiated from the oxygen sensor behind catalytic
converter via a 6-pin connector.
Special tools, testers and auxiliary items required
‹› Hand multimeter (V.A.G 1526) or Multimeter (V.A.G 1715)
‹› Test adapter kit (V.A.G 1594)
‹› Wiring diagram
Test Conditions
‹› Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670) -position 5- must be OK, check:
‹› Battery voltage (both batteries) must be at least 11.5 Volts.
‹› All electrical consumers such as, lights and rear window defroster must be switched off.
‹› For vehicles with automatic transmission, selector lever must be in " P".
‹› Parking brake must be engaged.
‹› The Ground (GND) connections between engine and body must be OK.
‹› Exhaust system must be properly sealed between catalytic converter and cylinder head.
‹› Coolant temperature must be at least 80°C => [ Diagnostic Mode 01 - Read Current System Data ] See: Powertrain Management/Computers and
Control Systems/Testing and Inspection/Scan Tool Testing and Procedures/Diagnostic Modes 01 - 09, Diagnostic mode 1: Check measured
values; PID 5, Coolant temperature.
‹› Oxygen sensor heaters for oxygen sensors before catalytic converter must be OK, checking => [ Oxygen Sensor Heaters Before Catalytic
Converter, Checking ].
‹› Fuses in right instrument panel fuse holder must be OK:
Right instrument panel fuse holder