A8 Quattro Sedan V8-4.2L (BGK) (2006)
Oxygen Sensor: Testing and Inspection
Heater For Oxygen Sensor Before Catalytic Converter, Checking
Heater for Oxygen Sensor before Catalytic Converter, Checking
‹› Oxygen sensor signals are monitored via On Board Diagnostic (OBD).
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Check DTC memory. If an oxygen sensor malfunction relating to heating circuit is displayed.
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Disconnect respective harness connector for oxygen sensor.
2
4-pin harness connector for Heated Oxygen Sensor (HO2S) 2 (G108) and Oxygen Sensor (O2S) 2 Heater (Z28) before catalytic converter, bank 2
3
4-pin harness connector for Heated Oxygen Sensor (HO2S) (G39) and Oxygen Sensor (O2S) Heater (Z19) before catalytic converter, bank 1
Test Prerequisites
‹› The respective fuses of Heated Oxygen Sensor (HO2S) (G39) and Heated Oxygen Sensor (HO2S) 2 (G108) must be OK:
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Coolant temperature must be at least 80 °C => [ Diagnostic Mode 01 - Read Current System Data ] See: Testing and Inspection/Scan Tool Testing
and Procedures/Diagnostic Modes 01 - 09, Diagnostic mode 1: Check measured values; PID 5, Coolant temperature.
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Perform continuity test (resistance measurement) between terminals 3 and 4 of respective sensor connector using portable multimeter (VAG1526).
Specified value at room temperature: 2.5 to 4 ohms
‹› At higher temperatures, resistance climbs sharply.
If specified value is not reached, replace respective Heated Oxygen Sensor (HO2S) (G39)/Heated Oxygen Sensor (HO2S) 2 (G108).