Grand Prix V6-191 3.1L (1989)
and/or loads to confirm. See "Fuel System Diagnosis" CHART A-7.
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Exhaust Leaks: If there is an exhaust leak, the engine can cause outside air to be pulled into the exhaust and past the sensor. Vacuum or crankcase
leaks can cause a lean condition.
^
If the above are OK, it is a faulty oxygen sensor.
