Does that hose that you detached look clean on the inside? Have you inspected that plastic hose for cracks? Mine became brittle and cracked.

With the hose detached from the SAIP, does the pump make good pressure during a cold start? It should be really loud turbine like noise when running.

It could also be the vacuum hose to the combi-valve or the solenoid that supply the vacuum to activate the combi-valve. If you detach the vacuum hose at the combi-valve and cold-start the engine, you should be able to feel vacuum pressure at the hose. If you have the OEM vacuum hoses they may break or crack after a few year. I have several posts on this (you can search by poster name) as I have been trying to fix this code for a while.

Good luck.

 

With the hose detached from the SAIP, does the pump make good pressure during a cold start? It should be really loud turbine like noise when running.

Thanks Airboy, I will check this tonight, all of the hoses looked fine. So if the pump isn't making pressure with the hose detached, it would indicate a bad SAIP as opposed to the Combi Valve?

 

Just make sure the engine is cold, otherwise the ECM won't switch on the pump. I usually leave my hood open, remove the plastic engine cover and use a floor-standing fan to cool the engine down unless it had been sitting for the day/night.

As you mentioned, a bad combi-valve can lead to pump failure...does the detached air pump hose smell like exhaust? According to Sharky, that is a sign of a bad combi-valve.

 

from a VW/Audi tech tips circulated to dealerships:

In the event you have an A4 1.8T with engine code ATW with the DTC of 16795 - Secondary Air Injection system, Incorrect flow Detected, a leaking Combination valve could be the problem. A leaking valve causes exhaust gas to enter the secondary air system. The water from exhaust condensation travels through the entire secondary air injection system and if the temperature drops below 0 degrees Celsius the water will freeze. In most cases the water causes the air pump to corrode. Inspecting the combination valve will reveal the problem. If the Intake side of the valve is black, exhaust has entered the secondary air injection system.

 

... If you have the OEM vacuum hoses they may break or crack after a few year.

Correction: they WILL break or crack after a few years.

 

Thanks for the info modifiedA4. This just plain SUCKS!!!! IF this is my problem (Code P0411), then this will make the 2nd Combi Valve and 2nd SAIP I will have put in the car in less than 100k miles, all due to water getting back down into the SAIP during the winter months!! This really burns me up! All they would have had to do was build a water trap into the line to keep water from running down into the SAIP, and then the only part needing replacement would be the Combi Valve. But no, now it'll be $240 for the SAIP (again!) and 120 or so for the Combi. I love my Passat, and I'm glad it's not something that affects driveability, BUT money down the toilet is still money down the toilet, plus the knowledge that most likely, I'll have to do this again in another 40k miles!!!

 

Thanks for the info modifiedA4. This just plain SUCKS!!!! IF this is my problem (Code P0411), then this will make the 2nd Combi Valve and 2nd SAIP I will have put in the car in less than 100k miles, all due to water getting back down into the SAIP during the winter months!! This really burns me up! All they would have had to do was build a water trap into the line to keep water from running down into the SAIP, and then the only part needing replacement would be the Combi Valve. But no, now it'll be $240 for the SAIP (again!) and 120 or so for the Combi. I love my Passat, and I'm glad it's not something that affects driveability, BUT money down the toilet is still money down the toilet, plus the knowledge that most likely, I'll have to do this again in another 40k miles!!!

you are misunderstanding the failure mode....

the water is in the exhaust gas stream, a water trap wont do much.

anyway, have you checked to see if the vac-line to the combi valve is good?

 

I agree check your vaccum lines first. Had the same code on my old VR6, turned out it was indeed a bad vacuum line. Good luck!

 

from a VW/Audi tech tips circulated to dealerships:

In the event you have an A4 1.8T with engine code ATW with the DTC of 16795 - Secondary Air Injection system, Incorrect flow Detected, a leaking Combination valve could be the problem. A leaking valve causes exhaust gas to enter the secondary air system. The water from exhaust condensation travels through the entire secondary air injection system and if the temperature drops below 0 degrees Celsius the water will freeze. In most cases the water causes the air pump to corrode. Inspecting the combination valve will reveal the problem. If the Intake side of the valve is black, exhaust has entered the secondary air injection system.

I practically wrote that whole thing like 4 and a half years ago. I'm still bitter I never got credit for it.

 

I practically wrote that whole thing like 4 and a half years ago. I'm still bitter I never got credit for it.

which whole thing? the vw/audi tech tips monthly circular, or just the kombi valve article?

 

which whole thing? the vw/audi tech tips monthly circular, or just the kombi valve article?

VW has had a tech tip about this since a long time ago, and they bring it out again every so often. I don't know how Audi does it, but on the VW side they just put it on a recording at the Tech Assist hotline like when you're on hold for someone.

It came from me.

 

VW has had a tech tip about this since a long time ago, and they bring it out again every so often. I don't know how Audi does it, but on the VW side they just put it on a recording at the Tech Assist hotline like when you're on hold for someone.

It came from me.

this is where i got it, check out the week of may 1st 2001.
http://web.archive.org/web/20020805063859/www.20vturbo.com/tsb/mirror/audi/techtips.htm

 

The date is about right....

 

modifiedA4, no I understand the failure mode. But some form of barrier to keep the moisture from migrating down to the pump (since it is the lowest point in the system) so that it doesn't fill up the pump (as was the case previously for me) wouldn't hurt. But, regardless, that doesn't appear to be my problem. I pulled the hose yesterday and the inside of the pump is as dry as can be. And, I blew air into the hose going to the Combi Valve, and it seems to be holding pressure (although I have my hose spliced together after it broke until I can get a proper replacement). I then pulled the vacuum line at the Solenoid (I've replaced all of my braided vacuum lines with normal vacuum lines after finding several cracks and breaks), applied a vacuum, and it not only held the vacuum, but opened the Combi Valve and allowed airflow, where previously I felt pressure buildup when I had no vacuum applied. I'm going to start with the defective hose between the SAIP and Combi Valve, since previously it was broken in two, and now may be somewhat restricted due to the nature of my "splice" and see where I go from there. On the plus side, it isn't causing any driveability issues. On the down side, I am in the process of trying to find a job in Denver, and if I am successful, will have to fix this issue before I can register the car out there (Denver and surrounding areas have emissions testing)

 

I have a check engine light on my 2000 vw jetta and it was code p0411. I bought a new air pump and put it on and the check engine still came back . I need a smog test too. I bought this used car. What should I do? What can I do? Is it the wires or the ?? You tell me . I need to fix it asap. I dont got enough for a mechanic I think but if I can fix it myself I will. Someone please help

 

You should post on the VWVortex website, this one is for Passats and they are not on the same platform.