Good thread, I just bought an OEM air box thinking that it would solve my check engine light. Returning P1421 and 1423 codes brought me here.
My light was intermittent at first, it would literally go on and off randomly for days/weeks/months at a time, until recently, it hasn't turned off in a month or so now.
Going to try Seafoam first
WTB: Complete e46 M3 rear end
Last edited by hi its me alec; 06-18-2013 at 09:26 PM.