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Discussion Starter · #1 ·
Has anyone ever replaced the Secondary Air Injection Solenoid Valve N112? In attempting to replace my vacuum lines I ended up breaking the plastic nipple on this item. How is it connected to the intake manifold? Can it be replaced without removing the manifold (please say yes!)? Is it an expensive part? Car runs with it broken but I get the emissions workshop message every time I go over 2000 RPM or so. Thanks.

--Erik
 

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The solenoid valves under the manifold are parts #46 in this pic (two of them). Elcats lists the part number as 026-906-283- H. If that's right these things are over $130 each on vwparts.com :shock:. You may want to swing by the dealer parts counter and make sure you have the right p/n.



The combi valve attaches to the exhaust manifold, not the intake manifold, so I don't think that's the part we're talking about.
 

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Discussion Starter · #5 ·
$130? Ouch.

Do you know what type of screw #56 is? I can't get a good look under the manifold to determine what type it is. Thanks.

--Erik
 

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Not offhand, but I'll check my Bentley and post when I get home. Before spending 130, I'd recommend trying a high-temp adhesive - can't hurt, right?

What year/engine type do you have? (Engine type is a three-letter code stamped on your engine block lifting lug, under the black plastic cover. I'm guessing you have an AWM, but post and let us know).

BTW, you can get access to all this by taking off the "snorkel" hose and the throttle body. Flipping the coolant tank out of the way helps too.
 

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Discussion Starter · #7 ·
I have the ATW engine. I didn't remove the throttle body because I didn't have an extra gasket and I hate reusing gaskets.

Makes sense on the adhesive. I still think I need to remove the unit to properly glue it, but it's definitely worth a shot.

And oh, I have the printed Bentley and it doesn't indicate what kind of screws they are. Thanks for checking, though.

--Erik
 

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I also have the ATW 2000passat 1.8turbo dohc and have check engine light and p0411 code. i bought an EGR valve on advice of friend but it didnt fit- was returned -Is there a N112 and is it called Secondary Air Solenoid or Control valve.I was told by a mechanic it might be that--I have over 200k miles on the car.Do I need to lookup my info using the Vin number?Also I bought a refurbished Compressor- had it installed and now hearing a noise whenever in idle after motor is warm and Im at the stop light or sign- Putting it into Park kills the noise- Is my tranny going???Help.need a good vw mechanic in queens NY
 

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The N112 switches vacuum on/off to the combi valve to open/close the passage way from the SAIP to the exhaust flow. It is part of the SAIP system and could cause a P0411 but I've followed a lot of SAIP problem threads and it has never been identified as the root cause of the issue.

Usually a P0411 is caused by a bad SAI pump, cracked or missing hoses from the pump to the combi valve, bad combi valve, or broken vacuum lines that cause the combi valve to not open/close correctly. Also, once one part of the system is broken, other parts can follow. Eg, if the combi valve is stuck open, exhaust will flow back into the SAIP and condense there which can cause water to pool inside the pump and ruin it. Ditto if the pipes coming from the pump are broken as water will get into them and ruin the pump.

There are plenty of threads here on P0411, read through those or just check you-tube for info on how to systematically debug the SAIP.
 

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x2 on everything Iowegian said.

The ECM tests the SAIP system when the engine is warmed up and at idle. For me, at a stop sign a mile from home. It just runs the SAIP pump (blower) and opens the valve for a few seconds, then expects to see the O^2 sensor reading spike up from the fresh air. If that doesn't happen, it sets the P0411 code. It's a pretty thorough test.

A very common issue is the SAIP relay, which is in the ECM box, labeled 373. The relay is undersized--mine lasted about 10 years (I owned my Fresco Green 1.8T from new). A failed 373 relay will prevent the SAIP from running (or sometimes cause it to keep running) which will, of course, set the code.

The N112 valve is simply a small solenoid valve that switches engine vacuum to open the Combi valve (sometimes mistakenly called an EGR valve). The N112 valve is probably the least likely thing in the system to fail.

The vacuum hoses are another problem spot. I did a "replace vacuum hoses" writeup some years ago; it's in the knowledge base. The photo below is from that writeup.

98029
 

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The N112 switches vacuum on/off to the combi valve to open/close the passage way from the SAIP to the exhaust flow. It is part of the SAIP system and could cause a P0411 but I've followed a lot of SAIP problem threads and it has never been identified as the root cause of the issue.

Usually a P0411 is caused by a bad SAI pump, cracked or missing hoses from the pump to the combi valve, bad combi valve, or broken vacuum lines that cause the combi valve to not open/close correctly. Also, once one part of the system is broken, other parts can follow. Eg, if the combi valve is stuck open, exhaust will flow back into the SAIP and condense there which can cause water to pool inside the pump and ruin it. Ditto if the pipes coming from the pump are broken as water will get into them and ruin the pump.

There are plenty of threads here on P0411, read through those or just check you-tube for info on how to systematically debug the SAIP.
Thanks again!
 

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Your noises are most likely worn engine and transmission mounts. Check those first.
i KINDA KNOW WHAT KNOCKING MOUNTS SOUND LIKE FROM MY OTHER CAR- FORDS WERE FAMOUS FOR THAT.WHAT I DID WAS TO HAVE THE COMPRESSOR REPLACED AS A RESULT OF ANOTHER REPAIR WHICH INVOLVED THE TENSIONER(THE MECHANIC GOT A TOOL STUCK IN THERE AND SET THE WHOLE BALANCE OFF OF THE BELTS..) THERE WAS A VIDEO ON THE INSIDE OF THE COMPRESSOR(BELT DRIVEN) AND THE FAN BLADE LOOKING THINGS INSIDE AND HOW THEY COULD BE A NOISE PROBLEM.WELL I REPLACED THE COMPRESSOR WITH ONE OFF EBAY THAT KINDA HAD A DISCLAIMER- SAID IT WAS REBUILT IN 2010 - REALLY CHEAP :( BUT THE INSTALL WAS 300!!! I KINDA STARTED HEARING THE NOISE AFTER THAT INSTALL.DEAR LORD FORGIVE ME FOR TRYING TO KEEP MY CAR LOL
.ALSO SINCE I HAD IT I NEVER HAD A TRANNY TUNE UP -IT WAS SO DIFFERENT FORM AMERICAN CARS TO ACCESS AND CHECK THE FLUID- WILL DO THAT NEXT AS I SAW THE VIDEO WITH THE PUMP UP PROCESS ETC.IVE HAD THIE CAR ABOUT 8 YEARS NOW AND ITS GOT OVER 200K ON IT.THANKS GUYS FOR YOUR RESPONSES.
 
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