A3 1.6 se fault codes

[Killakam78]

Hey guys,

I scanned the misses 2004 A3 today with an OBD scanner, had 4 codes come up but i cant seem to find any staright forward answers to the faults just wondering if anyne could break the codes down into smple terms as i a novice with mechanics and trying to learn as much as i can.

Codes are

17698 i know this is to do with the coolant temp sensor - i believe that this is the ne n the RAD

18359 - cant make sense of

17811 - egr valve? Not sure what that is - is it the butterfly n the TB

18358 - fan control curcit - this would be related to the issue she is having with the fan being constanly on. Looking around on various forums it seems this is a common fault on the 8p but there are no resolutions for the isssue

Any help would be greatly appreciated on the above

[Killakam78]

New code came up today 16687, the car is misfiring really bad, from looking this up it seems to be a misfire on cylinder 3, plugs we're done some time last year, the acr is ticking like some kind of air leak, has any one had this issue?

[Killakam78]

Can anyone point me in the right direction for how to's on the BGU engine code?........