They're probably intimately related...

The times you describe the lights dimming are the times the SAIP (secondary air intake pump) should be running. And the SAIP not running would cause P0411.

So, there's probably some issue with your SAIP. Maybe it's seized, or full of water, causing it to pull more current than it should. But that's a little puzzling, since a seized SAIP should blow the fuse pretty quick.

The 40 amp SAIP fuse and the 373 relay that activates the SAIP are in the ECM box. Removing either the fuse or relay will disable the pump--try that and see if the light dimming goes away. Then the fun begins--search on P0411 or SAIP for more on the SAIP system. BTW, park the wipers up, then remove the plastic plug above the driver's wiper shaft for access to the fifth bolt that holds the ECM box cover on--you'll need a long, skinny, extension.

The relay and fuse are the only things between the battery and the SAIP motor, so be careful. But you can test run the SAIP by removing the relay cover and pressing the contacts closed with a tool (not your finger!).

 

Thanks for the tip on removing the fifth bolt. I'm definitely going to have to remove the fuses and see what happens, if anything.

A bit more info. Just got back in from starting the car this morning with my stopwatch handy. The flickering lasted for ~50 seconds. I stopped the timer a few seconds after the last flash should have happened and didn't, and had 58sec on the stopwatch. So 50-55sec was the duration of the flashing. With the windows down, I also heard a bit of a "screech" noise that almost sounded like metal on metal somehow... I put my foot on the gas an revved the engine a bit, and the timing of the flickering and noise did not change, but the noise got higher in pitch with the speed of the engine. Not sure if that helps at all, but more evidence can't hurt. I'll do my best to get into the ECM box and remove the fuse and/or the relay and start the car and see if there is any change.

Thanks,
Joe

 

FG is spot on, but I'd say at this point, I wouldn't bother with opening the clamshell just yet. Do a more basic test -- before the next cold start, go under the passenger side of the front bumper (remove the belly pan) and unplug the saip connector. If the flickering still happens, you have electrical issues.

Test your alternator. And might as well test the battery -- how old is it?

411 can be annoying, and you should fix it, but concentrate on your flickering for now.

 

Just got back in. With the relay and fuse removed, no flickering. I guess I'll go out and unplug the SAIP tonight and then late tonight or early tomorrow morning, fire up the car and see what happens. If the pump being unplugged also stops the flickering, I guess I'll have to get that pump replaced to solve both my issues. I'll update the thread once I've tested as GLInick suggested.

 

Looks like the belly pan is attached with several screws, at least one of which is way back there in the center of the car, correct? Would I have to lift the car to get at that to remove all the screws and get the belly pan off?

Also, I'm not sure on the age of the battery. I bought the car from my sister a year ago. I don't know how new the battery is, but based on the evidence so far, I believe the alternator and battery are both doing fine right now, or I'd expect issues that wouldn't go away after a minute of the car running.

Thanks,
Joe

 

By removing the fuse you just proved that the saip is the culprit. So no need to run unplug the saip. In fact remove that fuse to deactivate the saip until you are able to fix it. You will have the 411 until then.

 

I unplugged the SAIP before going out to see a movie tonight. Got back, fired it up, and no problems with the flickering. Definitely 100% a bad SAIP that is somehow failing in a way that when it turns on, it sucks a huge amount of power and causes all the other systems to lose some power for a bit. Will have to replace that or have my mechanic replace it. Is it difficult to replace the SAIP on my own? It didn't look like there was much to remove to get it out while I was down there unplugging the power, but I didn't pay lots of attention to the whole area when I was just unplugging it. If it's not terribly intricate to just raise the front end and get under there and remove it, I'd love to save the labor costs and replace it myself.

Thanks for all the input and help with this--I appreciate it!
Joe

 

You can definitely do it yourself. Do you have access to a bentley? I think one of the bolts may hard to get to from underneath but I read a couple of threads where people found a trick to get to it.

You've got nothing to lose. Start taking it off and if you get stuck you can always take it in. Just be careful with the flex tubes that attach to the blower housing. Don't use too much force. Others reported they became brittle and broke.

Once you take it out might as well hook it up to 12VDC to confirm it is seizing. And look for water in the housing in case your combi is shot also.

You can just use car ramps on the front wheels and you won't have to figure out where to put the jackstands.

 

I'm not sure what a Bentley is--please fill me in on that. You're right--it certainly can't hurt to get it up on ramps and play around with removing it. Thanks for the heads up on the likely brittle flex tubes.

-Joe

 

The "Bentley" refers to the official VW Service Manual for the car. (It's published by Bentley Publishing, hence the name.) It's available in paper and electronic form; most people here prefer the paper. It's considered by many to be the most valuable "tool" (besides PassatWorld, of course) for working on your B5.

Amazon has it for $90 new. Bentley Paper Repair Manual VW Passat (B5) : Amazon.com : Automotive Used prices (on Amazon at least) seem to also be about $90...

 

Thanks! That definitely seems like something I should invest in soon. My car is at the age where all the little things are starting to need repair/replacement/etc.

-Joe

 

Thought I'd give an update. I went to replace the SAIP today, and I removed the first hose and water came out. Didn't bother to go any further, since I had to order an EGR/Combi valve today to install. I knew there was a good chance I'd find water in the pump and have to do the combi valve, but I was really hoping to not have to spend the money, so I didn't order one with the pump. Looking back now, I wish I'd have done the obvious thing and bought the valve at the same time since my research showed the bad valve is almost always what causes the pump failure.

Once I have the valve and new SAIP installed, that should be the end of the P0411 problem for me. Only thing left that might still be suspect for the P0411 is the vacuum hoses, but since the Combi valve is bad and that killed the pump, I'm pretty sure I won't have to deal with faulty vacuum lines quite yet. Those probably will end up going to hell sometime in the near future, but at lest that will be a cheap fix compared to SAIP and Combi valve...

Thanks,
Joe

 

Popped the hood to look at the area where I'll be working once the Combi valve arrives. I took a picture since I have a couple questions I'm hoping you all might be able to help me with.

(don't mind the cream-colored splatter...I need to clean off the entire engine after I restored my headlights with the 3M kit a couple weeks ago)

The Combi valve is the silver part below the black part at the back of the engine, correct? I spent at least an hour searching for combi valve threads and videos online, and it seems the back of the engine is the location. What is that black part, and are there any hoses in the area that I shouldn't remove when accessing the combi valve area? It wasn't as easy as I thought it would be to find diagrams of all hoses in the engine compartment, but I think it's just PCV and vacuum hoses back there. I just want to make sure that if there are any hoses that I should really avoid to prevent other possible issues, that I mark them before I start and make sure I don't make anything worse while removing and replacing my combi valve.

Any help and guidance would be greatly appreciated!

Thanks everyone; you've been incredibly helpful as I get my baby back to running properly!
Joe