E36- Have OBDII codes p1423, 1421 and 0420. Planning on replacing the faulty o2 sensor this weekend and take a look at the Secondary Air Intake Valve. Before I replace the pump itself, does anyone have any suggestions on how to determine if in fact the pump is still functioning? Or is it almost a given that, based on the three codes above, the pump is dead?
Thanks
I have had the same problem on my E36, except I didn't have the 0420 code. No it's not "a given" that the pump is dead.
When the engine is cold, and you start-it, the pump makes a noise like a vacuum cleaner for about 90 seconds until the engine warms up. It's also not too difficult to remove the pump and run it directly from the battery to test it.
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