A6 Quattro Wagon V6-2.8L (AFC) (1995)
Heated Oxygen Sensor: Testing and Inspection
Checking Oxygen Sensor Heating
PROCEDURE
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Disconnect Heated Oxygen Sensor (HO2S) harness connector on right or left cylinder bank.
2 Pin Harness Connector
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Connect multimeter (Fluke 83 or equivalent) between connector terminals 1 (GND), and 2 (B+).
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Start engine and let idle.
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Specified value: approx. 12-14 volts.
If specified values are not obtained:
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Check HO2S fuse S28 (red fuse holder, engine) in central electrical system.
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Check continuity in wiring from connector terminal 1 to fuse using wiring diagram.
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Specified value: maximum 0.5 ohms.
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Check continuity in wiring from connector terminal 2 to GND.
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Specified value: maximum 0.5 ohms.
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Check fuel pump relay.
If the specified values are obtained:
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Connect additional test harness VAG 1315A/1 into 2-pin HO2S connector.
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Switch multimeter to 10 amp (DC) measuring range and connect (connect test harness to 10 amp connector).
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Start engine and let idle.
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Specified reading: 0.5-3.0 amps.
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Current (amperage) decreases as sensor temperature increases.
If specified reading is not obtained:
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Replace heated oxygen sensor.