When you say the air pump and air pump system "checked out" what do you mean? Is your mechanic experienced with Volvo's? 442 and 448 are codes indicating there is a flow fault in the pair system (the air pump). Most commonly will be the SAS valve which allows fresh air to flow to the cat to help reduce emissions on cold startup. If the SAS valve is leaking, it will cause a CEL.
There are a bunch of other codes that a car will set besides the O2 sensor codes.
What about the EGR system code? 442 and 448 are not related to the EGR. Was there another code?
Are you sure the codes were not P0442 and P0448?
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