well to start of to much air=lean not enough air =rich
i had it were on bank to was giving me both codes even though the o2 were new NGK
so after some more reading these vehicle are pickie i bought 2 new BOSH o2 reset ses
after 10 miles no more codes but now i would get po430 for the same bank 2 WTF
with NGK only 2 same codes with BOSH only 430 code also the mass airflow controls the air to fuel mixture for both banks guys were using the k&n filter and the oil would get on the element and give the lean or rich code also if the upstream o2 is loose same
thing and at time even though the ICV sounds good when shaken it doesn't really mean it is good meaning it might not be opening or closing like it should on mine with out AC on i get a certain fuel trim reading then when ac is on they go down
but the rule of thumb is lean=more air than fuel rich=less air more fuel
a friend of mine with same problem did a adaptain reset with inpa and it went away

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4/02 x5 3.0i AUTO BLACK
KISSIMMEE FL