Originally Posted by redlightning
,and all he did was some welding on the exhaust system.
key phrase right there
all my exhaust welds are done with a 90* bracket and a hose clamp that when on the pipe, give me a handy place to connect the ground to the pipe
ive seen MANY MANY techs slap the ground on the frame while welding a new exhaist tip or muffler on .... pretty easy for power to travel up the ehaust (because chances are its rubber mounted) and into the ECU through a coolant sensor or something
incredibly rare, but possible
i dont see how disconnecting the battery raly makes a difference tho, all your doing is decucing the # of possible power supplies from 2 to one ...