70k doesn't seem terrible. Cheap fix to do at that interval. NGK's @ $8ish/ea is only $48. I could live with that.

That said, are you using factory coils or aftermarket for the replacement? Any other stored or pending codes?

Hope your plug swap gets you at least another 70k without p0301, heck maybe you'll get to the 100k mark.

Edit: I usually use the NGK iridium single electrode plugs and have had really good luck with those on all my BMW's. Well, all except one... my custom turbo charged 318is e30. But that last one was my fault. Had to change those every 15-20,000 miles.

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)