2004 Honda Pilot 170,000. Past few weeks developed hiccup/slight hesitation at idle. Perhaps coincidence (or not) but developed after I replaced gas cap that wouldn't click on. Anyway, today check engine light comes on and after a few minutes VTM-4 light. Still car ran ok. Restarted car and engine light still lit but VTM-4 light came on after a few minutes. Same hiccup/hesitation at idle. Ran coder and found codes as indicated. Where do I start and what's progression to diagnose and fix? Thank you and Happy 2020!