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Danny, VW Mechanic
Category: VW
Satisfied Customers: 4004
Experience:  ASE Master Certified with L1 Certification, Volkswagen Certified, VW and Audi repair shop owner
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I have a 2000 VW Beetle turbo. Air pump is loud like a jet

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I have a 2000 VW Beetle turbo. Air pump is loud like a jet engine also error code P0411, i read on the web these pumps leak and create this noise, so I believe i need to replace area seems tight to work in so how do you remove the air pump

If you have a load secondary air pump and an incorrect flow code then more than likely either the vacuum line that goes to the combi valve is broken, or the combi valve is plugged or something. It's loud because it can't push the air it is flowing into the exhaust. A loud pump will not cause this code. Follow the hose back to the little valve near the back of the engine and check the vacuum line that goes to it to see if it is broken. If it isn't broken then follow the vacuum line to the little electric solenoid it goes to and follow that vacuum line as well.

If all checks out there measure the resistance of the solenoid and see if it is good.

The pump is close to $600 new, it is almost never that, I've replaced one or two of them but it was because the combi valve failed and the customer ignored the check engine light.

If you don't find anything with the combi valve then let me know and I'll explain how to get the pump out. I just don't want to waste your time because that's not the problem.

Customer: replied 8 years ago.

Ok I will check it out in the AM , if I disconnect the air house to that valve Combi if air pump noise goes away then it the valve's issue.

Is this electic solenoid a switch that turns on the vaccum to the combi valve?

Just trying to understand what the functions of items in question are.



You are correct about disconnecting it, although the pump may be damaged at this point already so the noise may not go away. My trick is to use a hand vacuum pump to open the combi valve, this rules out the rest of the system.

The electric solenoid does turn on the vacuum to the system as you thought.

I've only seen 1 bad solenoid, probably 1 or 2 bad combi valves, 20 or 30 broken vacuum lines for this concern just to give you an idea. If you need more assistance let me know.

Customer: replied 8 years ago.

THANKS Danny, did what you suggested,

Pulled the vac line from the combi valve and hose from air pump.

could not blow air from air pump hose, used hand vac on combi line and Combi valve opened up.

Now I have to wait for the engine to be cold and leave the aip pump hose on and use the hand vac.

If still noise will pull air pump hose..

Any thing else you can suggest?

Last is if it's the air pump how to get at it, small fingers???




I would pull vacuum like you stated and see what happens.

Leave everything hooked up and pull vacuum and see if the noise goes away. If it doesn't pull the hose from the combi valve (the one coming from the air pump) and see if the noise disappears.

The combi valves/passages can get clogged.

The reason I'm saying it isn't the pump is because it's obviously functioning even if it is noisy, it's not the reason you have the fault code there's something else wrong.

Customer: replied 8 years ago.

danny sorry for late reply went on a business trip.

Worked on this last night.

Pulled the hose from the air pump and yes some noise went away.

But the air pump is very noisy even I turn off the engine pump whines on the slow down, seems like bearing noise.

So I think I have the two problems, like you said I think the valve is somewhat plugged not all the way but some restriction, with this seems the pump bearing are going.


I will check one more but I think you gave me good advice.

One last is how to pull these items seems area is tight and don't want to remove more then I have to.




The combi valve can be removed without removing much else. We use special long allen head sockets that have a ball end on them so you can get at it from an angle. It's been a while since I've done the pump but I can check on it. I'll be removing a head from a 1.8T Jetta in the morning, I'll take a look at the pump and see how to get it out. If I recall you have to do it from the buttom.

The most common thing is that the combi valve fails, causes excessive pressure, and that kills the pump. Personally I'd wait to see if the pump ever fails because they're like $600 like I said and I don't know about where you live but in my area they don't leave that kind of stuff on the cars in the junkyard, they pull the motor. The thing only runs for a minute when the car is cold so when you drive places it probably doesn't even run when you come out of the store or whatever in the summer.

Like I said it's up to you and I'll try to remember to look tomorrow. If you don't hear back from me shoot me a reply, sometimes these conversations drop to the bottom of the list and I don't see them because I talk to so many people every day.

Danny and other VW Specialists are ready to help you
Customer: replied 8 years ago.


If I accept does this close it out or shall I wait for your reply..



Regardless of if you hit accept or not this thread will go away in a certain amount of time. I believe it's around 2 days or something.

Customer: replied 8 years ago.



Customer: replied 8 years ago.

Danny finally got around to change combi valve, air pump, place new vac hose to combi valve to electric solenoid, clear code and then P0411 comes back, what else could be causing this code.

Again this is on the 1.8l turbo APH engine.

any suggestions?


The solenoid could be bad, the vacuum hose from the manifold to the solenoid could be bad. I suppose there could be an obstruction in the big hose from the pump to the combi valve as well. Does the pump kick on when the car starts?
Customer: replied 8 years ago.

Yes the pump kicks on, seems also a P1128 error is now showing up.

So I believe you are on to the issue vac leak.

How best to find a vac leak?

Were should I test the vac and how much vac should I have, manual says 16-22 i believe.

Any suggestions on how to find where the vac leak is?



Under the intake manifold up front a couple vacuum lines go to that, including the secondary air injection line. I would check those first. You will probably have loosen the tray that's held to the intake manifold with two 5mm allen bolts to get in there and check the lines. My guess is the vacuum lines are unhooked. I wouldn't bother testing vacuum with a vacuum gauge as of yet. That's more of a test to determine engine issues.
Customer: replied 8 years ago.

Danny I am a bit confused on the 5mm allen bolts to get to the lines.

If I take off the plastic cover with 10mm nuts I see the intake manifold with the vacuum lines.

I will take a picture tomorrow if you could point the area's out.

Or if you have a picture that would be great.


Don't have the P1128 again after clear only the p0411 came back on.

I did do a check of the MAF and seems it is at 3.3 at idle but not the 50-60 when driving.

Could all this problems with P0411 be the MAF??


There should be another cover bolted to the front of the intake manifold with some vacuum lines. This picture shows an aftermarket intake manifold, but it also shows the second plastic cover I was talking about at the bottom of the picture near the dipstick. That's where the secondary air injection solenoid is.

Customer: replied 8 years ago.

Danny the picture is not showing up in the reply you sent.


Sorry here's a different one.

The small cover I'm talking about is right near the dipstick in this picture, the tray with the solenoid is under that.