Thread: E39 Faq
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Old 08-21-2008, 06:53 AM
djt5150 djt5150 is offline
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Location: Indiana
 
Join Date: Jan 2008
Posts: 97
Mein Auto: 2000 528i
Secondary Air Pump Problems

This seems to be pretty common. I'm working on mine right now. I did some research, and thought it would be a good idea to compile the good stuff here.

http://www.bimmerfest.com/forums/sho...d.php?t=265604

http://www.bimmerfest.com/forums/sho...d.php?t=260211

These are some good discussions on the air pump system/problems/solutions/part numbers. What I'm finding out is that replacing the valve and the air pump may fix your CEL for a while, but there may still be problems. For instance, when I took off my old air pump, being the curious person that I am, I took it apart (you pretty much have to tear the pump into pieces - but I knew it was bad so what the hey) and found that it was completely melted on the inside. So I put the new one on and it did not have any power. I found the relay in the E-box and took it out. Jumped the big two wires together and the new pump came on (only works when engine is running - and cold). So my relay is bad - stuck in the "off" position. I must assume that the relay was bad earlier - and was probably stuck in the "on" position which fried my pump due to overuse.

So, everybody will tell you that when replacing the pump, go ahead and get the secondary air pump valve. I would take that a step further and say, go ahead and get the salmon colored relay for it, too. According to this research, these relays are a main culprit for pump failure (I'm not unique). Hope this helps somebody else.
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