A8 Quattro Sedan V8-4.2L (BGK) (2006)
If specified value is obtained, check voltage supply.
Voltage Supply, Checking
‹› The respective fuses of Heated Oxygen Sensor (HO2S) (G39) and Heated Oxygen Sensor (HO2S) 2 (G108) must be OK:
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Connect voltage test lamp (VAG1527) between terminal 3 of respective oxygen sensor connector and engine Ground (GND).
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Operate starter briefly.(Do not let engine run longer than 2 minutes, because of malfunction entry)
Voltage test lamp must light up.
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If voltage test lamp does not light up, check wire connection from terminal 3 of the respective oxygen sensor connector via fuse to Fuel Pump (FP)
Relay (J17) for open circuit or short circuit.
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If fuses and wire connection are OK, but voltage test lamp does not light up anyway, check Fuel Pump (FP) relay => [ Fuel Pump Relay, Checking
].
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If voltage supply is OK, check wire connections.
Wire Connections, Checking
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Check the following wire connections using portable multimeter (VAG1526).
Heated Oxygen Sensor (HO2S) (G39) before catalytic converter bank 1, with Oxygen Sensor (O2S) Heater (Z19)