# Secondary AIR Pump & Combi Valve



## rocketmann (Mar 2, 2007)

I just replaced my Secondary AIR Pump for the second time in 13 months. It cost $700 (would have been $900 at the dealer).
The local mechanic said it was full of water and claims that the water got in there because my bottom engine cover is missing. I said to him that the pump is pretty well sealed and I can't imagine how occasional splashing up from the ground could cause this, and that the water probably got in there from _internal, not external_ sources. He had no answer. I also asked him about the Combi valve. He didn't seem to know what it was -- he said something about the turbo, and then said all the hoses and everything else looks good, it's just a bad pump and I should get a new bottom cover.
I think the guy is very good at installing SAPs for $700 a pop, but really doesn't know how this all works. So now I'm in a position where I'll probably be installing another pump for $700 before too long unless I take some pre-emptive action. So what should I do?
1) Should I just have the combi valve replaced?
2) Should I disconnect the electrical plug from the SAP, and reconnect it for a day when I go for inspection?
3) Is there a fuse ONLY for the SAP that I can pop out?
4) Something else?
Spending $700 a year for this can get tiring.


_Modified by rocketmann at 11:23 AM 4-26-2010_


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## J377AR1D3R (Feb 26, 2009)

*Re: Secondary AIR Pump & Combi Valve (rocketmann)*

are you sure its your seconary pump or is it the hose that is from the seconary. i had a problem with my seconary air pump before. i changed the hose than i found out that my pump was bad and i went to home depot got some machine screw and nuts fixed the pump. now it runs like new.


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## travisjb (May 25, 2007)

*Re: Secondary AIR Pump & Combi Valve (J377AR1D3R)*

your "guy" does not sound like he knows 1.8t's very good. get a vag com scan, and then you will know what to do.


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## herb2k (Jul 29, 2007)

*Re: Secondary AIR Pump & Combi Valve (rocketmann)*

Some common issues: 
1) Rivets on the pump go bad, and the pump can't hold enough pressure. Fix: Get some small nuts and bolts and replace the rivets on the pump. 
2) Combi Valve: Check that it is getting vaccum (there is a tiny vac hose that goes into the back of the valve, it may have come loose or gotten loose over time as the rubber stretched out). 
There is also a procedure for checking the combi valve when you remove it from your car, air should only pass through when vaccum is applied to the small nipple at the back.
Trace the vac line from the back of the valve to the solenoid underneath the bracket in front of the intake manifold - check for leaks, etc. 
If it's allowing air to pass in both directions regardless of whether or not vaccum is applied, then you do indeed have a bad combi valve, and this could cause the condensation to build up in the pump destroying it over time.
3) The obvious: check the corrugated air hoses, they often develop cracks over time. 
FWIW: You can't really disconnect the SAI before an inspection because that would throw a code, and readiness wouldn't be set. You might be able to "trick" your car that the SAI is working properly so that it sets readiness, but that's about it.
In most cases, a VAG-COM scan will only say "Secondary Air Injection: Incorrect flow detected". Unless it's a solenoid or pump electrical failure, the generic code won't help point you in any direction.


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## rocketmann (Mar 2, 2007)

*Re: Secondary AIR Pump & Combi Valve (travisjb)*

Travisjb,
<< get a vag com scan, and then you will know what to do. >>
Well, the pump was already changed so I can't undo that. I don't have a Vag Com, and the local auto parts stores that check your codes for free only have a basic scanner, not a Vag Com. 
In any event, what I really want to know is what pre-emptive action to take to avoid replacing the SAP again. From everything I'm reading, the water does not get in there from splashing up from the ground; it gets in there due to a faulty Combi Valve allowed moist exhaust gas to flow back to the SAP, where it condenses and gathers. If that's the case (and tell me if you think it is) I want to know what action I should take today to prevent a problem in the near future.


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## rocketmann (Mar 2, 2007)

*Re: Secondary AIR Pump & Combi Valve (herb2k)*

Herb2k,
I assume I'd have to remove the pump to change rivets. The pump in the car now is brand new.
Where is the Combi Valve? Do you or does anyone have some pictures they can post? I would almost be inclined to change it myself if it's not too difficult. Do you know easy/difficult a job it is for a semi-novice?


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## herb2k (Jul 29, 2007)

*Re: Secondary AIR Pump & Combi Valve (rocketmann)*

I changed some of my rivets with the pump in place. You can just unbolt it, and disconnect the lines and then spin it around under the car. Since yours is new, I don't even think rivets are an issue in your case.
The combi valve is right under the intake air tube, on the driver's side of the engine. Looks like a little flying saucer thing (just follow the plastic air tube) - should be held in by two torx bolts to the engine block.
I don't think it would be too difficult to get at (you might have to move things around) but it's pretty easy.
*EDIT: Just noticed you have a passat - the location might be different on yours! But you can still just follow the corrugated plastic hose to the combi valve to find it*
Check the small vac hose behind the valve though before you do anything, as that's the easiest. On my car it looked connected but when I pulled on it, it just slid off without any effort! 


_Modified by herb2k at 10:30 AM 4-26-2010_


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## bootymac (Apr 19, 2005)

*FV-QR*

While we're at it, I have a CEL for "SAI - Improper flow" and I haven't had any luck finding the problem. Checked over the SAI and concluded that I didn't need to replace the rivets. The SAI's respective hoses also look fine, so I'm not sure what's causing the improper flow code. 
Any ideas?
Edit: Upon looking over the combi-valve as mentioned above, the vacuum line appears to have a crack in it. Would a leak here throw the improper flow code?


_Modified by bootymac at 11:53 AM 4-26-2010_


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## J377AR1D3R (Feb 26, 2009)

*Re: FV-QR (bootymac)*

it could be your seconary pump air hose. take the hose out and check it. and while you at it check your pump too..


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## herb2k (Jul 29, 2007)

*Re: FV-QR (bootymac)*


_Quote, originally posted by *bootymac* »_
Edit: Upon looking over the combi-valve as mentioned above, the vacuum line appears to have a crack in it. Would a leak here throw the improper flow code?

_Modified by bootymac at 11:53 AM 4-26-2010_

Yes, it would! In my case the hose was just not fitting the fitting tightly enough, causing a leak (been plaguing me for almost 2 years now). But the vaccum line is very important, without vaccum to the combi-valve, it won't open enough or at all so the ECU won't read the proper flow.


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## bootymac (Apr 19, 2005)

*FV-QR*


_Quote, originally posted by *herb2k* »_
Yes, it would! In my case the hose was just not fitting the fitting tightly enough, causing a leak (been plaguing me for almost 2 years now). But the vaccum line is very important, without vaccum to the combi-valve, it won't open enough or at all so the ECU won't read the proper flow.


Thanks for the feedback, I'll replace the vacuum line today. I thought I screwed something up with the SAI when I was changing the engine speed sensor, but I must have damaged the vacuum line during my K04 install instead. It's always something


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## rocketmann (Mar 2, 2007)

*Re: Secondary AIR Pump & Combi Valve (herb2k)*

Herb2k,
I assume I'd have to remove the pump to change rivets. The pump in the car now is brand new.
Where is the Combi Valve? Do you or does anyone have some pictures they can post? I would almost be inclined to change it myself if it's not too difficult. Do you know easy/difficult a job it is for a semi-novice?


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## herb2k (Jul 29, 2007)

*Re: Secondary AIR Pump & Combi Valve (rocketmann)*


_Quote, originally posted by *rocketmann* »_Herb2k,
I assume I'd have to remove the pump to change rivets. The pump in the car now is brand new.
Where is the Combi Valve? Do you or does anyone have some pictures they can post? I would almost be inclined to change it myself if it's not too difficult. Do you know easy/difficult a job it is for a semi-novice?



Assuming your 1.8T is mounted longitudinally in the passat, it's probably going to be towards the firewall side of the engine, so you'd have to do some reaching.
Just do as I said in my previous post and follow the plastic air hoses to the combi valve.


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## rocketmann (Mar 2, 2007)

*Re: Secondary AIR Pump & Combi Valve (herb2k)*

Herb2k,
Can you or someone specifically describe the flow scheme of the combi valve? (Pictures would be great) What goes in, what goes out, how is it controlled. In other words, what does it do and how does it function?


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## herb2k (Jul 29, 2007)

*Re: Secondary AIR Pump & Combi Valve (rocketmann)*

I don't have one - there might be a nice diagram in the FAQ.
Basically, vaccum is applied to the valve (the N112 solenoid controls this) to open it during a cold start up and the SAI pump is engaged. This runs for about 90 seconds - when the valve is open, that fresh air is pumped into the exhaust stream in order to heat up the catalytic converter faster (I'm not sure of the exact science). 
All other times, there is no vaccum applied and the valve should remain closed. This keeps exhaust gases from leeching into the SAI hoses and pump which will cause condense as it cools, causing the pump to corrode internally and seize up.
Edit: this is the diagram from the FAQ: http://forums.vwvortex.com/zerothread?id=2666114










_Modified by herb2k at 1:51 PM 4-27-2010_


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