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Secondary Air Pump Check Valve Problem

62K views 24 replies 15 participants last post by  Stickbuilder 
#1 ·
So I have the check engine light on and I had the dealer diagnose it, and what they told me the problem was, was the secondary air pump check valve. I tried to have the guy explain it, but only being a service rep he had no clue. I only have a slight clue, so I am here to ask you guys. I'm not sure what this is, or how to fix it. If I am not mistaken this shows the secondary air pump; http://www.realoem.com/bmw/showparts.do?model=AV33&mospid=47720&btnr=11_2203&hg=11&fg=45
I also know from replacing the valve cover that when I was in there I saw the hose (part #3 on that page) is broken. So could this be my problem? Also what effect does it have on the engine?
 
#2 ·
disconnect the vacumm hose at the control valve item #1 (known as EGR valve). ask someone starting the car and you feel whether it has any vacumm. If no vacumm, then check the hose all the way back to the check valve (item #5) to see any damaged or cracked. if hose OK, then your check valve may be bad.
 
#3 ·
disconnect the vacumm hose at the control valve item #1 (known as EGR valve). ask someone starting the car and you feel whether it has any vacumm. If no vacumm, then check the hose all the way back to the check valve (item #5) to see any damaged or cracked. if hose OK, then your check valve may be bad.
You have to check for vacuum when the engine is cold. There is only vacuum for the first 30 seconds or so.
 
#5 ·
I got the P0491 and P0492.
My Pump comes on fine. But when starting the car when the pumps on I Cant feel any exhaust air blowing back through the valve. Shouldnt This be happeing for like 30 seconds?

So I Guess I need to check the Small vacum hose on top of the valve? I guess this has a vacum for a few seconds to open the valve right?

So I need to see if im getting a vacum on start to that small line and If i am Probably bad valve and if im not i guess i need to move down the line and check that hose for cracks?
 
#8 ·
Pump shuts off after a minute or two you know.

But, try this...

First squeeze the big hose from pump to valve...if it's squishy, remove it from valve and look inside the valve inlet.

I had a failed hose...deteriorated right through...I suspect from having sucked in oil vapor from bad vcg...anyway, it had corroded thoroughly and sent a ball of gunk into inlet of valve...causing my car to stall until I, maybe not so intelligently, started it a third time and before it stalled, I gunned it. I think that sent the ball of gunk into valve and it did take a while to clear.

Anyway, I replaced the hose...I also, maybe not so intelligently, opened up the pump, removed filter from the top (irreplaceable and also a bit dirty...but it's still okay)...anyway, on advise from a fanatic (also, maybe not the brightest thing knowing what I know now), I sprayed WD40 into pump...while holding the disconnected end of hose away from me and car (that 'was' a good idea).

I also took dental pick and removed said ball of gunk from valve inlet. I know they fail, but in my case, all is still good...maybe two years later (forget when this happened but I did post shortly thereafter).

Also, I did notice a crack in the hose leaving the back side of valve...a little dab of rtv to seal it up...it's all been good since. I should've replaced the entire hose, I know, but as I'd done enough work on my car at that time, was looking for a shortcut, so made one up. I got away with it is all I can say.

Hope this helps.

Doug
 
#9 ·
After replacing parts with no success clearing the CEL, I decided to push Seafoam though my secondary air ports.



You can only push Seafoam through the ports while the engine is cold and the secondary air pump runs. The low secondary air flow is based on the air flow to the o2 sensor. Carbon blocked ports restrict the flow below the level that trips the CEL.
 
#11 · (Edited)
http://forum.e46fanatics.com/showthread.php?t=809715

My recent fix

Next time its cold, pull the vacuum line off the valve, it will prolly break if its original, anyway, check it for a vacuum. You should feel suction. If you feel nothing, see the link above. If you do feel suction, attach it back to the valve. Disconnect the air pump hose from the valve. Feel by the valve for exhaust gas. If no, valve is likely bad. Just follow that bavauto article and the link above if your getting no vacuum to the valve.
 
#12 ·
Thanks That Guy great thread.
BUt NOw i Cant get any power to the pump now I let it sit all day while i was at work and againg later its 30F or less here Pump wont kick on Pump Is Good.
Also Put a new relay in the 50amp Fuse is good and so is the F2 and F3 under the hood. So I guess i need to figure out if theres another fuse or something??? Or What tell the car to fire up the pump???

Please help This is my wifes car and i just need to get it to pass inspection i bought this car like 3 months ago one thing after another, Done Oil Sepaerator about 4 windows regualtors, Oil filter housing, I Can go on and on all the regular E46 stuff ive about done
 
#13 ·
To check the pump just take it out and run power to it directly via a jumper wire from battery and a ground. If you can get the pump to run by jumping it the pump is good and it might be something else along the line that's bad... but you said you already did the relay, and fuses are good. Not too sure. When you say relay, you are referring to the Salmon colored relay behind the glove box right? And you checked the regular fuses in the glove box as well right? If the pump ends up being bad let me know I have a spare sitting around I'll let go fairly cheap.
 
#16 ·
If there is 12v to the pump while the engine is cold, then the pump is not good. If there is not 12v to the pump when the engine is cold, then the relay or the fuse are not good.

The pump takes 12v and a pretty high amperage, so you can simply unplug the pump and connect the pin on the pump side of the connector that does not go to the BRN wire on the car side of the connector to the + terminal located nearby, and connect the pin that is connected to the BRN wire on the connector to ground, and the pump should run. If it does not run, it must be replaced. If it does run, then you have a problem in the wiring -- fuse, relay, or wires.
 
#18 ·
If there are any secondary air pump codes stored, the pump will not run.
The engine coolant temp must be between -10C - 40C
O2 sensors must be in open loop mode
O2 sensor heaters must be operating.

If the engine temp is less than -10C the pump will only run for a few seconds to blow out any condensation that might be present.

Take a look at this document for more info - pages 33-34
http://www.beisansystems.com/misc/SEIMENS_MS_420_ENGINE_CONTROL_SYSTEM.pdf
 
#20 ·
Working on the Pump Side of the connector, connect a wire to the + terminal for the jumper cables, and another wire to ground. The pump will start.

The diagnostic tool will test the entire circuit, but if the pump doesn't run with jumpers, then the pump is bad, if it does run, then the rest of the circuit is bad.
 
#22 ·
vacuum line

I unplugged the vaccum line to the valve but couldn't feel much suction. Is the suction strong and easily noticeable?
If I don't feel suction, should I just go straight to replace the line, although I don't see any noticeable cracks. well I haven't removed the air filter casing to check the back yet..
 
#23 ·
In order to see the entire vacuum hose from the vacuum source to the check valve. you need to remove the coil cover and the injector cover. Then you can actually see the small vacuum line and associated hoses. Chances are that you have one or more fractures of the vacuum line/hose along the exhaust manifold part of the system. I found several breaks on mine, and restored the function of the Secondary Air System by replacing the entire hose. Route it as it came, and you should be good.
 
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