u/Braaapus_Maximus80fo

Recently had my tires changed on my 2015 street Bob. On the ride home my check engine light came on and is throwing a P0134 code. The O2 sensors have been bypassed on this bike( it was like that when I got it.) I’ve put over 3000 miles on it and never had a CEL before. When the dude changed the tires, he had to pull the exhaust so he could get the rear axle out. Would an exhaust gasket leak throw a code even if the sensors have been bypassed? I know he didn’t put new gaskets in when he put the pipe back on. I torqued the flange nuts later on myself to no avail. For all I know they might still be the original gaskets in there. Any advice on this is greatly appreciated.