I have a 2002 A4, with 62K miles. recently i started getting a CEL with error code P0411. I reset the error code a couple of times hoping it was false trigger but it keeps coming back.
Any suggestion what I can do to fix the problem (other than taking the car to the dealer).
people suggested checking for cracked hoses that come off the air pump. The problem is I donlt knwo where the air pump is
Any suggestion would be greatly appreciated.
A few things to check in the morning (cold engine)
Listen for the secondary blower to run (100 seconds after engine start-up). This sends air to the cyl head via the EGR valve. Make sure the vac hose going to the EGR valve is intact. Make sure all the plumbing for the secondary air pump is in order.
Possible problems include a plugged up EGR (combi-valve) valve, a bad secondary air pump, blown secondary pump fuse.
Nick, it's ok to use the "subject box" to enter new text and if you run out of room conti-
nue here. At this time with all my wisdom and knowledge of 30+ yrs with VAG I'd say your secondary air pump is running but may be going south and your EGR "combi valve" needs to be replaced. The latter may be a dealer warranty/recall/bitchaboutit item. Depends on the MMY (make.model.year)
Easy little quick test for the secondary air pump.
Engine cold. Locate the SAP inlet pipe, it gets it's air from the air filter box. Twist the pipe from the AF box (about 1/4 turn) Start car, go back under hood, place thumb/palm of hand over the pipe you just dis'd from the AF box. You should feel noticable suction. If not the combi-valve is likely bad or vacuum supply to it is. Now to help comfirm, repeat all steps above but take the other (pressure) side pipe off at some easy location before the combi-valve and repeat cold start engine procedure. If you get suction and discharge from both the pipes you have loose this will prove that the SAP is good and the EGR/Combi-valve is indeed bad/clogged up.
hoses, vac lines, and those check valves all get krusty
i destroyed my evap return line with a blowout and have been living with this code need to bust out the jack and replace it.
if i fill up i have difficulties starting for the first 2-3 starts.
to complicate matters i've been running USP $1.64 check valves in place of stock ones but this issue didn't come up until the passenger tire took out the wheel liner and the hose from the N80 to return hard line. tried to patch it no dice. $60 later i got a new hose.
the no start after filling up was definitely new after blowing out the tire and shredding that vac hose so i guess its pretty important to have proper evap flow. feels like vapor lock
I was all ready to start doing some testing, but I finally got a chance to look at the car this morning. I just had the timing belt replaced and the turbo inlet hose replaced, so lots of things were touched in that area. Sure enough, I followed the hard pipe from the check valve next to the purge valve down towards the air box and right there, a hose sticking up at me attached to nothing. I reach down to the hard pipe and I feel the end. Simple connection that either wiggled free after the TB work, or more likely just a simple oversite when putting the front end back together.
I cleared the code, clamped the hoses together, and the issue is resolved. No parts to buy, and maybe 30 minutes of my time taking the air inlet and headlight out to get my hands down in there.
2002 A4 1.8T M/T quattro
APR Stage 1, snub, TIP, 710N DV
Neuspeed Short Shifter
Koni FSD/Eibach/H-sport S4 sways
B5 S4 front brakes, Porterfield R4S
Stoptech SS lines
Dunlop SP Sport 01/Yokohama AVID H4S