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Old 04-21-2011, 10:03 AM
Got_boost? Got_boost? is offline
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Location: Seattle
Join Date: Apr 2011
Posts: 5
Mein Auto: 2004 BMW 745li
Loosing my head, looking to get help from community. Secondary air flow

whats up people. i ran into some issues with my 2004 BMW 745li and just cant seem to figure it out. i know there is some smart people out here that could help me out.

to start off, i got a check engine light, and it read P0491. So i immediately did some research, and came up with insufficient secondary air flow bank one. then i did more research and it said that it should be the passenger side bank, either the valve or the hose with the y connection under the intake manifold. So at cold starts, the pump starts buzzing and then it shuts off in like 30 seconds after cold start. so i determined that pump was good. I then ordered a new valve and a new y hose so i can tackle the problem. i replaced both, and made sure everything is plugged in and good n tight. torqued the manifold and connected everything back.

I then started the car and the code was off for a lil while but it came back on with the same code. so im lost. I dont know if the drivers side valve could cause this, but i know that bank 1 is passenger side. If anyone has any imput to shed, please do so. I read every single post on this on bimmerfest and still couldnt come up with something new.

I also have another question, if one of you 2004 745li owners could do me a huge favor. i saw in some posts if you have problems with vacuum lines, or maybe the ccvv, it can possibly throw this code. so i realized on my car that i have the pressure regulating valve on the valve cover thats possibly missing a hose to connect to the nipple. and then i saw on real oem, that i also need to have a pressure regulating valve on the passenger side of the engine valve cover, right behind the oil cap. now if someone could clarify this for me, it would be greatly appreciated.

heres the first pic, with the valve circled in red.

and the second pic is of the passenger side and it looks to me like it needs to have the same valve, right next to the oil cap.

and here is from real oem a pic, i put my vin number, and this is what they gave me.

any helpful input is really appreciated, i need to pass emissions so please help a fellow brotha out!
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