A4 Quattro Sedan L4-2.0L Turbo (CAEB) (2009)
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Using a multimeter, check the Heated Oxygen Sensor (HO2S) (G39) terminals 3 to 4 for resistance.
Specified value: 2.5 to 10.0 ohms (at approx. 20 °C)
If the specification was not obtained:
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Replace the Heated Oxygen Sensor (HO2S) (G39).
If the specification was obtained:
Checking voltage supply
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Crank the engine (engine may run).
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Using a multimeter, check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 4 to Ground (GND) for voltage.
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Switch the ignition off.
Specified value: Battery voltage.
If the specification was not obtained:
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Check the Heated Oxygen Sensor (HO2S) (G39) electrical harness connector terminal 4 to the Motronic Engine Control Module (ECM) Power
Supply Relay (J271) socket 8 an open circuit, a short circuit to each other, Battery (+), or Ground (GND).