o2 sensor DIY here. i was off a little. upstream are easy. did them myself in 20 minutes last week. downstream look a little more involved, but still doable.

LINK

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2005 X5 3.0i - 71k mi (9.2018) -> 81k (9.2019) -> 100k (9.2021) -> 123k (8.2025)
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SOLD : 2003 X5 3.0 - 177k mi (9.2018) -> 186k (9.2019) -> 205k (9.2021)
SOLD : 1997 328is Coupe - Hellrot Red
SOLD : 1988 528e w/ Bullseye s256 / MS2 Extra / GC Coilovers / Yukon Coils ~ 300+ HP