The battery is ok but engine won't fire.
my 2004 audi turns over but won't start. Why? on 2004 Audi A6 Quattro
You need to check for 2 things: fuel and fire. Is the engine getting gas? Are the sparks plugs firing? You can try to spray some starting fluid in to see if it will start. Do you have a check engine light on? If so, get code read please and post.
I get an EPC code
This stands for electronic power control. Which is the drive by wire accelerator and electronic throttle body system. Need to get codes retrieved to further diagnose the issue.