Gas Certificate

Any leak can allow carbon monoxide from the burner to leak into the living area.
Carbon monoxide is deadly. It kills.
Treat the problem seriously.
Cheers,
Peter
OKA196 motorhome

"I need to seal behind the fridge as light coming through."

The light is coming through where? Please give a detailed description of the situation so we can can give you a sensible answer. The model number of the fridge will assist as well as not all the fridges are installed the same way. I refuse to comment on the info you supplied in case I gave you some bum info.

An easy way to seal is to use flashing tape available from Bunnings. The glue on that stuff is legendary.
I have fully sealed my fridge back for insulation , so that no heat from the coils goes down the sides of the fridge.