Derives from Mojo meaning hip, cool, sexy & soulful.
Fauxjo is something or someone trying to be cool & look like they have Mojo but failing. A bit like in 'Pretty Fly For A White Guy'.
Relic'd guitars are a good example. The ones where someone gets a new guitar & then puts loads of dents & scratches on it so it looks like they've been playing it for 40 years.
"Look at him with his fake vintage Guitar."
"Yeah, he's oozing fauxjo."
Or someone who goes out & buys a job lot of 60's Soul records & then pretends they're some sort of knowledgeable record collector who's been into the music for decades.
Or cars like the New Beetle or New Mini which look a bit like the old ones but have none of the character or Mojo, just Fauxjo.