I'm sure that was a stressful moment!
I know that even an improperly crimped coax on a BNC connector on the back of a VHF radio can mess with the aircraft's instruments.
And EMI is not unique not just aircraft, but I had a fire engine that had a bad PL259 connector on the back of a Kenwood lowband that when keyed, would propegate into the electronic engine controls and rev the engine. Not good - especially when the fire truck was sitting at a stoplight and the engineer had to talk to dispatch.