getting the following fault code from vag com - 17545 - fuel trim bank 1 (add):system too rich. it gives possible problems with the maf, injectors, o2 sensor etc. can anyone advise on how to narrow it down to the problem. am i right in thinking it probably isn`t the maf as it is an add reading and not mult. this is the first time i have used vag com and am not sure how to use the measuring blocks to find more specific problem. i am thinking of cleaning the maf or replacing the o2 sensor. i know were the maf is but not the o2 sensor. is it easy to replace ?? any advice would be greatly appreciated as i can`t really afford to go to audi at the moment.