HI lads new on this site from ireland .I have a problem from the weekend i was trying to solve mt A/C PROBLEMS so i was tryin to find A/C relay while doing this i had engine running and took out relays in engine compartment fuse box and wen took one relay out engine shut off so put back in started fine no problems idle is fine but when i went to drive it later that day i found no boost from turbo in my mk 5 2005 gti and CHECK ENGINE light on,so i put on a vag computer and its telling me number <3 cylinder knock sensor> is gone so i rang vw dealer and they said very unusual as they never give trouble on them ,so i was wondering has anyone had a problem like this all information is greatly appreciated cheers paul .