Had my Sons Polo looked at by a very kind garage that used a VCDS to check the codes. Below is the result - 3 intermittants and a normal one. The codes have been cleared which has cleared the Orange engine warning light and has stayed off for 10 miles driving back.
I know it is not an Audi, but does anyone have any clues what may have been the problem - specifically the non-intermittant code 16804. It is a 1.2 E '52 plate