The snowscreen is an air intake snorkel with a screen that keeps out large debris and snow out of the air intake box. If it gets clogged with mouse nests or leaves, a spring loaded auxiliary intake flap opens, preventing the engine from air starvation. If the aux flap spring is rusted or the door is stuck, the engine will be air restricted. This aux air is somewhat warmed by the engine and is not as good as cold intake air but if it's working it prevents the engine from stalling.
Mann makes the OEM VW air filter so it's a good filter. The cold climate air filter has an extra foam layer on the bottom.
The replacement interval is 40,000 miles. Change the cabin air filter as needed, once a year is suggested.
Parts (click links to compare current prices)
1 new engine air filter - either:
Cold climate engine air filter (with extra foam layer) VW# 1J0 129 620 or Mann filter from kermatdi
Non cold climate engine air filter VW# 1J0 129 620
1 new activated carbon interior air cabin filter
a brush or compressed air to blow out screen
All you have to do is unscrew the top cover to the air box. (2 phillips screws). Mine were rusty so I used a dremel to cut a groove in them and then used a standard screwdriver to remove the screws.
If you need more clearance, remove the MAF electrical plug and unclamp the accordion like hose if you want. I also suggest vacuuming out the bottom of the air filter box and cleaning the snowscreen while you are in there. Make sure the tabs all fit into their slots and that the air filter edge gasket is seated properly.
These cars are known for slow MAF failure. If your car has been losing
power, a faulty MAF may be responsible, see 1000q:
limp mode, 1000q: constant low power or
can't rev, and 1000q: a4 MAF for more details. If you determine that the MAF is bad and
need to remove the element, a special VW tool is required to
remove the MAF screws. You could also use the dremel to cut a groove into
it and just replace them with normal screws. Most MAF come as a whole unit
with the plastic and require no special tools to remove.
Very easy but here's a video anyways. There's unnecessary music in the
video so don't bother turning up the volume.
Note that in the below pictures, the air box and battery were removed for clarity.
Remove (1x 10mm) nut circled in yellow and pull out the intake snorkel.
The snowscreen is at the end of the snorkel. Use water or compressed air to clean it
out and then replace it. I do not recommend cutting the snowscreen
out since it prevents larger debris from reaching the air filter.
Here is the spring loaded dooropened partially.
Remove the 4 phillips screws (one is circled in red) and pull up and away the
rubber weather stripping on top of the firewall.
Pull out the plastic trim and the cabin air filter. During reassembly, the black plastic frame has 2 tabs on the top front
edge and 3 tabs on the
lower rear edge. 1 of the tabs is marked in red.
Vacuum out any dust/dirt and replace the filter and
trim. The ribbed cylindrical object below the air filter is the blower fan. If a leaf gets caught in there it'll rattle.
I prefer activated carbon filters since the activated carbon absorbs odors.
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