My 2004 Chevy Express 3500 Van has a 6L V8 gas engine and is a Class B Roadtrek Motorhome. When setting for more than a month, I use Battery Tender Junior 12V to maintain battery. Also, when it sets for more than a month and when first starting, it runs rough and the engine light flashes. After turning it off and restarting, it no longer runs rough and the flashing engine light is off. When setting for a month, I can avoid this problem by immediately by driving off when starting and not idling. There is no problem if it sets less than a month. Any ideas what is causing this problem? Thank you, Mike

 

If the engine light flashes then it has stored a code. What codes has it stored?

 

Thanks. I will borrow a code reader. Mike

 

No codes

 

swing by an Autozone and have you battery load tested for free