Check Engine light

Hey guys,

So about two months ago I removed the charcoal filter in my air box. Noticed a great improvement in throttle response. About 2 weeks ago my check engine light came on. Then it went off. Then it came on and went off again. Finally about 3 days ago it came on and stayed on. Checked the code. It said it was the MAF. I saw some posts about cleaning the MAF and stuff so I cleaned it. Car has run great the past days until now. The light has come back on. I have not coded it yet to see if it is the same thing but I have a feeling it is. So has anybody had this problem before? Do I need to buy a new MAF? Or a new air OEM air box?

Thank you

I don't think the MAF issues could be caused by removal of the filter, as people remove the stock airbox all the time to install a cold air intake with no issues.

Also, how did you remove the charcoal filter? Is it just glued in?

Well the definition for the code was air/fuel ratio was off. Found information about that leading to the MAF. I cleaned the MAF and the SEL went off so I assumed that was the cause but like I said it has come back on.

I took out the air box, opened it up to replace the replaceable filter, and then cut out the charcoal filter. I didn't sand down the edges, but I did wash it heavily twice and dry it. (The MAF was taken out of the box before washing happened)

I had this happen before, 3 months after replacing OEM air filter with the K&N oiled filter I got the SES light with the same code. MAF was replaced at $450. I thought it might have been a coincident or that MAF was due because it was near 100k miles.
Less than a year later the same thing happened, but this time I just used the "CRC MAF cleaner" and switched back to OEM air filter. It fixed the SES problem.
I still have the old MAF for 2006 330xi that I saved that I suspected was slight contaminated as well (and I cleaned it with CRC). It's probably still good!

What did you clean your MAF with?
You can try to put in a new OEM filter (w/your charcoal modification) and see if SEL stands off.

I cleaned it with CRC MAF cleaner. I have an OEM filter in it right now. I cant put the charcoal filter back in unless I buy a new box. Any new OEM air boxes I have found come with a new MAF so I know I can fix the problem for ~450$, but I really like the much better throttle response. Was hoping to get the best of both but... maybe that's not possible

The car only has 75k miles on it. It is a n52 325i.