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Wolfgang, VW Master Technician
Category: VW
Satisfied Customers: 4519
Experience:  Senior VW Master Tech 15 yrs
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Volkswagen Rabbit 2.5: , I have a 2008 vw rabbit 2.5

Customer Question

I have a 2008 vw rabbit 2.5 .. have been getting code p042 & p044 for about 3 months now ..replaced gas cap and it didnt help....but car ran fine.... 2 days ago car started running terrible -misfiring and hiss in engine .. in addition to the previous codes I also now have 2 new ones ...p301 & p302 ... took off cover and pvc diaphram is definitely leaking.... question is where do I start ??? Do I just replace the pvc diaphram. .. or the whole valve cover ??? And are these codes related? ???
Submitted: 1 year ago.
Category: VW
Customer: replied 1 year ago.
I don't want to go to a dealer...
Expert:  Wolfgang replied 1 year ago.

Thanks for choosing Just Answer . I'm Wolfgang here to help!!

I am confident we can resolve your problem together. Please
understand that I don't know your skill level. In most cases when you have a problem
with the way the vehicle performs, specialized tooling is required to acquire computer
data/information or engine testing results. We didn’t build these complicated vehicles; we
just diagnose and fix them. Also understand that I can't see, smell, hear, or touch the
vehicle either, so it may take a few replies to get to satisfactory results. I am also going to
direct you with the fastest, easiest and most common things to check first. Please be
patient and permit me to do what I do best.
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
through it.
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail.

On your issue the whole valve cover to replace. i have seen kits to replace the diaphram but the success rate is about 35% . not worth the hassle.

the codes are a Pxxxx format so i need to know the entire code to assist!!


Customer: replied 1 year ago.
I figured that I should just replace the whole valve cover.... as for the codes...
P0440 & P0420 ...
P0301 & P0302 ...Thanks
Customer: replied 1 year ago.
As for my knowledge I am not a mechanic but I am slowly learning to do many things by default like I said I do not want to go to the dealer I have had bad experiences with them
I also have a 1972 Volkswagen Super Beetle in my garage that I am currently restoring so I'm learning more everyday.
Expert:  Wolfgang replied 1 year ago.

need to correct the valve cover first and then clear the codes and then road test . fyi you are talking to a dealer tech!!! the valve cover can cause all kinds of issues so lets go with the obvious and then continue then . but keep in the back of your mind of the other faults that you had!!

Customer: replied 1 year ago.
Thanks. .. I will order valve cover tomorrow I saw a great video on YouTube with step by step instructions. .. I'll get back to you after its done .... was just a little confused cuz from what I read online valve cover issues or PVC diaphragm issues would give different codes than what I was getting. But due to the loud hissing sound coming out of the diaphragm I would say it's safe to say replacement is necessary
Expert:  Wolfgang replied 1 year ago.

sure my pleasure!!

Customer: replied 1 year ago.
I changed out the valve gasket cover as discussed and car is running fine ... cleared codes and still get p042 & p044... what should I check next?
Expert:  Wolfgang replied 1 year ago.

the next thing is to chekc the canister purge valve. if you follow the vac hose above the throttle body to a black valve . first see the valve is leaking (not sealing)

Customer: replied 1 year ago.
I also changed the vapor canister purge solinoid valve. . Reset codes ... now I keep getting P0455 .. and both times I have gotten this code the gas cap warning light has gone on ahead of the check engine light going on ... I wasn't getting this code previously? ????
Expert:  Wolfgang replied 1 year ago.

the replacement was just in the rear? or did you also replace the valve under the engine cover/air filter housing on the passenger side?

Customer: replied 1 year ago.
I didn't do the one in the rear ? Did the one in front under the engine coverThanks. down the road wants to charge me 125 to smoke it ??? Should I change the one in rear first ? Is it the same one as in front ?
Thanks for the info/help
Expert:  Wolfgang replied 1 year ago.

The valve you replaced must be installed correctly due to the fact that the valve is flow directed . if installed backwards the tank system will not work correctly.

Expert:  Wolfgang replied 1 year ago.

i have a wierd question what is your place of residence? rural , city , lots of wildlife? any recent accidents?

Customer: replied 1 year ago.
There was a arrow on the part... I put it the same way... I could try turning it around. .. I live in Connecticut. ... no accidents... light has been on for a year ... finally fixing because I'm selling....
Expert:  Wolfgang replied 1 year ago.

no do not change the direction. the key is that if you live where you have alot of chipmunks or little critters that live around you.

Customer: replied 1 year ago.
I do ... and actually when I took the engine cover off the first time there was a lot of twigs and stuff that kinda looked like a nest .. didn't think much of it at the time ...
Expert:  Wolfgang replied 1 year ago.

i have a feeling on this that in the back there is some plastic corregated line that critters like to chew and nest on top of the tank. that smoke test is the next best thing to trace the leak !!! note it may be expensive if they have to drop the tank!!!..

Customer: replied 1 year ago.
So I had it smoked today at a garage. . He said there is a leak above right rear tire. Said it was in the vent valve. Said I could fix myself so I took it home .... went to try to buy vent valve ... cant find anything called that except fuel tank vent valve .. ? He said just take off tire and plastic cover and it's right there ... do you know what part that is ????
Expert:  Wolfgang replied 1 year ago.