Bay13, et al, Please explain what it means in real terms to have the fuel trim turned off when the air pump codes are displayed??? I just read this at the Bay13 Air Pump intructions.....implications related to air pump removal....

You will have no fuel trim adjustments, your fuel air mixture will not be correct, nor will it be adjusted to be correct. In time, you could destroy your O2 sensors, and maybe your Cat. In a state with emissions you will not pass emissions.
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Rich K.

Interesting. I have been sans air pump for over a year. I monitor my fuel usage and there has been absolutely no delta in mpg, (other than the normal tank to tank standard deviation) my car runs exactly the same and there are no other problems. (No signs of over rich/lean mix conditions) There must be some default to a control mode.

And yes it passed emissions last year.

Do you have a check engine light that is caused by the air pump setting codes?
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Rich K.

Yes.

In this state (VA) you can't pass an emissions inspection with the check engine light on. You were lucky. If your not noticing any difference in your fuel consumption or milage maybe you'll continue to be lucky. I only know how they are suppose to work, and how to fix them for the most part, don't really have a clue as to what you can get away with.
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Rich K.

Thanks for your excellent help. Your site is model of "how to" web sites....the photos are great. I just enjoy stepping through stuff I've already done....and wondering....what will be next!

In only selected areas in WA state (Seattle Metro) they just stick the sniffer up your....pipe....no idiot light review or hood popping.

Yes I am lucky because I moved to an area in WA with no checks at all.

So now - do you think the Fuel Trim is not disabled may be because the car is an M56 (vs. an AT)?