cold air intake o2 sensor

i had just installed a k&n cold air intake to my 93 325i , about 2 weeks later i installed a bav auto performance chip, drove great for about 3 weeks then all of a sudden in third gear at a steady idle speed of 3000 rpms my check engine light went on. had it diagnosed faulty o2 sensor . A buddy of mine said that its common when you install an intake and run on a factory exhaust , because it builds too much back pressure. is this true? the light tends to go off when i hammer it . if what my buddy says is true will this keep happening when i install the new o2 sensor? and is there a high performance o2 sensor on the market, or are they all the same?

actually, an engine can't draw in any more air than it can pump out, so, no, I don't agree with your buddy, the back pressure doesn't change, the amount of addition air drawn in is more than compensated for by the DME and I service a number of E36's and others with 'cold air' systems without problems. There are no 'performance' sensors or a need for them, they simply measure how much oxygen remains in the exhaust gas compared to the atmosphere and generate a some voltage signal so the DME can continually adjust the fuel quanity to keep the Cat. lit properly.

I think your O2 sensor simply gave up the ghost on it's own due to age.....THERE ARE more to O2 sensor codes than just 'faulty sensor' so beware, but it's common on early E36's to see them fail with age.

actually, an engine can't draw in any more air than it can pump out, so, no, I don't agree with your buddy, the back pressure doesn't change, the amount of addition air drawn in is more than compensated for by the DME and I service a number of E36's and others with 'cold air' systems without problems. There are no 'performance' sensors or a need for them, they simply measure how much oxygen remains in the exhaust gas compared to the atmosphere and generate a some voltage signal so the DME can continually adjust the fuel quanity to keep the Cat. lit properly.

I think your O2 sensor simply gave up the ghost on it's own due to age.....THERE ARE more to O2 sensor codes than just 'faulty sensor' so beware, but it's common on early E36's to see them fail with age.
thanks for the info the car has 120000 miles now. hope thats all it is is a worn sensor