I think it reduces the amount of unburnt hc's in the exhaust by pulsing air into it so stops the cat being 'poisoned' allows enough oxygen for oxidation. and I think has something to do with cold starting
does it stay up if you use global closing from outside the car (overides the safety trap feature) if so then yes the safety overide is malfunctioning. Glass isnt tight in the runners is it - try some silicone lubricant (could be as you said 'it lasted a week' this time~)
folk may be able to help if you give more details e.g age/mileage - put your car details in your signature line - click on the red link in my signature for help :D have a look here or here btw - welcome to the forum :o
I've heard this before, whats it all about? car lifted on the sills not the jacking points will result in the sill weld bending over - encourages corrosion later on :lol:
not indicated unless other signs are present - leaky air con is very common - poll on here indicates that half the peeps here have trouble, probably a leaky pipe, evaporator etc - glad the garage agreed to pay ;)
IIRC its not as simple as pulling off the door and mounting another, I think the hinges need individually welding into place :) so wht are you replacing with - if new problably doesn't have hinges if secondhand the hinge may not be in quite the same place
IIRC after 3 faults depending what they were eg Flameout which this sounds like, the ecu decides not to try anymore until codes are reset I suspect you need one of the uprated glowplugs and the fault codes resetting
Probably none but extended driving will get the element dirty - might need careful wipebut for a short time I expect it would be alright. Older style hot wire type would be more sensitive to dirt I would think