blitz28179

2009 GMC sierra 1500 V-6 What could be casuing it to short?

Well after getting a 02 oxygen sensor check engine light I decided to go monday to buy a oxygen sensor at advance auto.I was gonna take a chance and guess passenger side.I could never get passenger side sensor off.Its really in a tough area where its hard to reach with a standard sized tool.So I jumped over to driver side.It was alot easier to reach so changed it with new sensor.After installing driver side sensor I am still getting check engine light and ALOT more hesitation/stalling.My check engine light blinks when the truck starts stalling.My check engine blinked alot more than it ever has.So now I am getting worried so tuesday morning I decided to take it to a mechanic in my area to install other oxygen sensor on passenger side .I stayed with the guy and watched him.Well before he changed the passenger side he checked my fuse box.The fuse for the oxygen sensor was blown.He installed a new fuse and it blew too.He climbs under truck to unplug both senors and puts another fuse in.After turning switch it blows too. So he thinks my oxygen sensors are good that I have something wrong with wiring from fusebox to the end of the plugs.Any thoughts? Thanks in advance