I am getting a P1498 code along with SES as well as EML lights, when I installed my AGS I forgot to plug in my map sensor and this made the car miss real bad and I have been told that I may have killed downstream O2 sensor. I hope this is the case because I am @ my wits end on trying to figure out what is wrong with it.

 

are you sure that's the code you are getting. i can't find the code on the BMW list. the only one i found was this one:
P1498
Voltage Problem In EGR Valve Position Sensor Circuit (Acura, Honda)

apparently P1498 is honda specific???

if it's an O2 sensor it will be P0130-P0140. thats for the O2 sensor circuits. good luck!

 

I have dropped by advanced auto and had them run the code and also a friend has an OBD reader and his had the same thing, P1498=Auxillary emission control

 

Are you getting the mis fire when you are accelerating, and creates a back fire. i'm am pulling a p-003? code, but I agree this is frustrating. I changed the o2 sensor and spliced into the old harness. I think I'm going to have to get a whole new o2 harness and wire. I started to wonder if I had patially blocked my exhaust ports when I changed my header. Well I hope we both can find the problem.