# Hole on catalysor X3 F25 2011 with N55 engine



## Iso9001 (Jul 30, 2021)

Hi all.
While trying to replace my blow off valve on my X3 F25 N55 (2011), i saw this hole on the exhaust cat.
Is it normal?
Should I weld it?
Is it necessary to disconnect battery before welding?
Thanks


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