Passat L4-1984cc 2.0L DOHC (1991)
Oxygen Sensor: Testing and Inspection
Oxygen Sensor and Oxygen Sensor Control, Checking
Oxygen Sensor and Oxygen Sensor Control, Checking
Requirements
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engine coolant temperature 80°C (176°F) minimum
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idle adjustment OK
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no leaks in exhaust system between catalyst and cylinder head
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voltage supply for Oxygen sensor heater OK
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switch ignition OFF
For vehicles built up to 9-90:
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switch Fluke 83 multimeter to mA range
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disconnect differential pressure regulator (N 71) harness connector
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connect test adaptor VAG 1315A/1 between regulator and harness connector (arrows)
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connect multimeter to test adaptor VAG 1315A/1 using jumper leads from VW 1594 adaptor kit
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switch ignition ON
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control current polarity (90-110 mA) must be positive (+); if not, swap test connections
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start engine and let idle for 2 minutes minimum
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record control current
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clamp crank case housing breather hose 1
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control current must decrease
If NO