ive not been on here for a while so hello again . A friend has a 2.0 fsi 05 reg with 114000 on clock it just developed a missfire on cylimder 4 codes 16684 and 16688 changed spark plugs and swapped coil packs over plugs 1 and 4 looked damp this didnt cure the problem but noticed water level low and water vapour all over floor under exhaust could this me head gasket blown causing these problems or just an electrical problem. Thanks

i had same problem as above and did what you did. In the end i had to do all spark plugs and all new coils it solved my problem. if you can see if you can lift the coil on cylinder which you believe to have missfire? If so do this and listen out for spark. If theres a spark you can hear then it wont be coils.