Secondary Air Low

[BasilRathbone]

I’m receiving “Secondary Air Low” codes (F5 & F6) on my 2003 BMW 325i (E46).

Both the Secondary Air Pump and the Secondary Air Valve appear to work properly. The pump puts out air when energized and the Secondary Air Valve, when operated with a MityVac, both holds vacuum and opens and closes as it should.

I also tested the line between the Secondary Air Valve and the back of the engine and it holds vacuum and shows no leaks.

The MityVac indicates the vacuum source from the back of the engine is low – only a pound or two at best.

Where do I need to go from here?

[randy72877]

Check the vacuum solenoid that controls the shut off valve and the associated small vacuum lines from the intake and to the shut off valve by the front of the head.

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[BasilRathbone]

randy72877

Replacing the tubing that feeds the Secondary Air Solenoid Valve leads me to another question


I followed the rotted Secondary Air Solenoid tubing through the One-Way Valve back to a set of vacuum ports on the intake manifold – to a set of three vacuum ports in fact.


One of the vacuum ports was large bore (7mm ‘ish) and factory capped. (I had to replace the cap ‘cause it was old and cracked).


There were also two small bore (4mm ‘ish) ports.


I used the top small bore vacuum port for the Secondary Air Solenoid (I don’t think which port matters)


There was a remnant of either another hose or a cap on the lower small vacuum port. I looked around for a dangling hose missing it’s vacuum port but couldn’t find one so I ended up capping the port.


Do you happen to know if something once plugged into this port or was this port originally capped and the cap just fell apart over the years?

[BasilRathbone]

randy72877


Well that was fun ... not! I had to take the firewall and driver side panel out to get enough room to actually see and access the Secondary Air Solenoid and One-Way Valve … it all boiled down to 15 year old cracked and rotted German rubber tubing.


The Hans and Fritz engineers that ‘engineered’ where to hide the Secondary Solenoid Valve and One-Way Valve must have chuckled for a month over how folk were ever going to access them in case of failure. I still don’t have no clue how to actually get the Solenoid Valve out should I eventually have to replace it.


But the end result is I now have 1 atmosphere of vacuum at the Secondary Air Valve and the F5 and F6 codes haven’t returned – so thanks for the heads up!


I found this Pierburg and RealOEM link which may help those with the same issue(s) I had.


http://www.pierburg-service.de/ximag...106_en_web.pdf


http://www.realoem.com/bmw/enUS/show...diagId=11_2203

[BasilRathbone]

I found this link! http://forum.e46fanatics.com/attachm...6&d=1333856148

I recognize everything except hose 'B'!

What is hose 'B' connected to?

[randy72877]

Not sure but it could be for the exhaust flap. The link above didn't work for me.

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[BasilRathbone]

randy72877

Try http://icms.duckdns.org/files/vac-hoses.jpg

I'll leave the vacuum port plugged if hose 'B' only runs the exhaust flap.

Where does the fuel pressure regulator get it's signal?

[randy72877]

randy72877

Try http://icms.duckdns.org/files/vac-hoses.jpg

I'll leave the vacuum port plugged if hose 'B' only runs the exhaust flap.

Where does the fuel pressure regulator get it's signal?

Fuel pressure regulator is on the filter. It is not connected to vacuum. The hose that is connected to it runs to the F connector in the intake boot.

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