What valve did you replace? The check valve in the vacuum line or the air valve attached to the cylinder head?

If blower works and you have confirmed all vacuum lines intact with vacuum and all vacuum line check valves working, that leaves the air valve to the head not opening, a clogged secondary air system air filter, or a defective secondary air mass sensor.

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04 X5 3.0i auto
03 X5 4.6is