Originally Posted by
bmwagn
I am newbie when it comes to the e34 (1995 525it, with M50). I have always drove e30's. So here's the problem. Check engine light came on at 183k code 1221. I replaced the O2 sensor (BMW factory part), reset light went on about life. 194k check engine light back on code 1221. I have no coolant problems and no oil consumption problems but I do smell exhaust especially in the vents and and when I open the door after a short or long trip. Also before I changed the old one I noticed smoke occasionally seemed white but no real smell just exhaust smelly. The O2 sensor I pulled was slightly blackened with a eraser sized piece of black goo on the tip (it tested bad by meter). I am wits end and I am afraid that the new sensor will probably go bad. Any suggestions anyone?? Should I just go to bed and forget about it. Thanks in advance, Kelly Joe.