So, it has always annoyed me since buying the car that it was only fitted with 3 air filter box clips (the metal spring clips - the trickiest one at the bottom front was missing.  There is clearly a hole in the bottom filter box for a clip.

 

Finally got round to buying one from the dealers.  Got it in the hole after a bit of cursing; but it just pings off the lid!  I notice that the other 3 clips have an indent of sorts to clip into, whereas at this location the top lid doesn't have such a feature.  Now I'm wondering if they actually only fitted 3 on purpose (perhaps because of it's location damaging the big rubber hose that runs on top of it?

 

Does anyone else just have 3 clips?

I have four and the harder two to get at are a pain as they are tight to get on and often go for a walk. So I can imagine someone just lost one.

Thanks nackuk...

Hahaha you're going to laugh.

 

My filter box does have 4 clips fitted.  The 4th one I hadn't seen is on the side of the metal heat shield (like everyone else's, I guess!).  As I have pretty small hands I manage to get my filter in easily without taking the airbox out, and I've never had to loosen the bottom clip to get the filter in / out.  It was still firmly in place when I looked just now.

 

On the edge of the filter box nearest the front of the car there is another plastic moulding feature which is designed to take another clip.  Obviously the bottom of the filter box is designed to be used in another application with both clips on this side of the box.  I saw this empty feature and assumed I was missing the 4th clip.

 

D'oh >facepalm<