From Ross-Tech Wiki
16839/P0455/001109 - EVAP System: Large Leak Detected
- Gas Cap loose/missing
- EVAP System Leaking
- Check Gas Cap
- Check EVAP System
- Check to make sure EVAP purge valve is not installed backwards
- When found in any model with a Gasoline engine that had a replacement in-tank fuel pump installed make sure the brand new or revised fuel pump does not require a cap per the dealer parts catalog! Failure to install a cap (such as part number example: 8E0-201-263-G) when necessary may result in a serious safety concern!