Secondary air pump fault [Archive] - Bimmerfest - BMW Forums

: Secondary air pump fault

07-20-2010, 03:29 PM

I had the service engine soon light come on, saying there was an emissions related fault. Autozone read code P0491. When I took it to the dealer to get a diagnostic, he told me that the secondary air pump needed to be replaced with the relay at the bargain of $1015.

Of course, he cleared the code so I can't get a second opinion. On the printout, it just says:"Perform a short test. Fault for secondary air pump bank. 1. Test secondary air pump and the pump flows no air."

Does $1015 sound reasonable to replace the secondary air pump and relay? It says the parts cost $465. Does anyone have any suggestions on anything that I can check, and how long it should take the light to come on again?

Thanks. I just didn't want to be getting ripped off if it should cost less than $1015. :cry:

07-21-2010, 07:23 AM
If your ses light didn't immediately come back on, I doubt that it is either your pump or your relay. Having said that, it would assume that you have since started your car when it has sat overnite. The system reduces emissions at cold start and only works for a few minutes. Check all vacuum lines associated with the system. Especially the one that comes directly out of the top of the pump which is located on the passenger side front of the engine. It is about one inch in diameter and has those stupid one use only clamps on it. If you can wiggle this hose when you grab it then you have a leak. The rubber gets brittle and shrinks. You cannot tighten the clamp. Take off the old clamp and replace with a screw type clamp available almost anywhere. Worked for me.

07-21-2010, 07:45 PM
Thanks for your response. I was happy when I drove the car for 2 days and the light didn't come on... but it came on 52 miles later. So, I guess it is the secondary air pump & relay. I wish your diagnosis would've worked and the light stayed off!