S4 Sedan L5-2226cc 2.22L DOHC Turbo (AAN) (1992)
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Heated Oxygen Sensor: Testing and Inspection
Checking HO2S Sensor Signal
Oxygen Sensor Connectors 20v
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Fold back rubber boot at oxygen sensor lead 1, do not separate connectors.
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Connect Digital Volt Ohm Multimeter (DVOM) between exposed sensor lead and ground.
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DVOM should oscillate between 0.1 and 0.9 Volts
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If reading is fixed at 0.4 - 0.6 Volts, check for open circuit between sensor and ECM.
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If reading is too low, check for grounded signal wire, intake leak, or heater element operation.
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If reading is too high, check for signal lead short to other wiring.
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If wiring is OK, replace sensor and recheck.
