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secondary air pump low flow???

20K views 24 replies 13 participants last post by  zensaru 
#1 ·
I have a secondary air pump low flow in a 2001 325i.
The secondary air pump works the motor is not seized and i checked the hoses no leaks.
Any idea?


Any help would be greatly appreceated.

TIA
 
#3 ·
Ive never had this happen on my e46 but In my co worker's merc its a pump that goes out..the one that helps to warm up the catalytic converters.
 
#9 ·
Did you check the thin vacuum hose between the check valve and the vacuum control switch? I got the same error code (P1418) and isolated the problem to that hose.

Both very helpful thank you.

Well see i did check the hose it does indeed have cracking.
However i look at my car and my hose has the same amount of cracks one is a 2.5l and mine is a 2.8l now i dont think that would affect it.

I will follow the bavauto guide and get back to your guys.


Thank you for you help.
 
#7 ·
Pour Seafoam into the air hose from air pump to engine port before the engine is first started in the morning. The hose will hold just over an ounce of Seafoam. Reconnect the hose and run the car 5 seconds so the air pump blows the Seafoam into the exhaust port. Repeat this fill and restart 3 more times only running the engine 5 seconds so the secondary air pump runs. Then let the engine sit 15 minutes and warm up the car. There will be significant amounts of Seafoam carbon burnoff in the form of white smoke. The carbon burnoff will clean exhaust areas in the path to the O2 sensors that measure secondary air flow.
 
#12 ·
Mine throws the same codes when it is cold. I inspected the hose and it is good. Bought a cheap code reader/reset for about 30 bucks. I also squeezed the hose a bit. I plan on replacing it this winter. That code is really no issue though. Part of the emissions system and no big deal. Another thing to look at though is the sec air pump could be going bad. They are not cheap. If you go the SeaFoam route, like I did, do it right before you change your oil and have some time to blow all the crud out through the exhaust. Just my 2 cents.

EDIT: also check the clamps on the hose to make sure they are tight.
 
#13 ·
A common failure is with the pumps themselves. Inspect the pump very thoroughly. You wana look at the rivets holding the pump case/housing together. Over time, the rivets will break and if you look closely, you'll notice the pump case splitting apart at the seems. If it turns out to be the issue and the case has not split/seperated very much, you can use small nuts and long skinny bolts to tighten the pump case/housing back together, so to say. This will typically cause erratic sec. air flow faults since some of the air flow leaks out of the pump case..............
 
#14 ·
The code will not let the vehicle pass emissions so i am trying to get this sorted out.

The pumpp is working i have tested it and it looks fine no problems with it at all but i will continue to check it today and let you guys know my fionding.

Thanks for all your help
 
#22 ·
I'll often put a large flat head screwdriver in between a hose and the fitting and just turn it a little to 'wedge' it out a tad...speeds up the wiggling, but remember, the SAP is plastic, so no banging or prying!

You could also remove the hose from the valve instead to check air flow...but, if you're just doing this to futz around with things, I'd just 'feel' the hose, and if it's squishy, leave it on and order another one...not too expensive.

I've also had a crack on the vac line as Ciand mentioned...for me, a little dab of rtv sealed mine and saved me the headache of replacing it...at the time I didn't know it was easy-ish...but it's held for a year like that.

Doug
 
#25 ·
Having the same problem (2001 325xi). I had my mech go through the bavauto PDF linked above and he found the power connector to the secondary air pump was loose/corroded. Cleaned up and reattached, pump runs correctly.

Once this problem is fixed, does anyone know how/when the code is reset? Trying to get this to pass emissions. My mech says it needs some number of cold starts to clear the code, but I'm wondering of that is just a rule of thumb on his part?

Once all the secondary air components are running properly, does the 'Low Secondary Air flow' code clear immediately or not?
 
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