TD4 Oil Leak around Oil Filter / Filter Housing

Have a slight oil leak around the oil filter cap / oil filter housing.

I'm gonna swap the O ring when I get a replacement, but if that fails, I'm guessing that it is either a cracked cap or the gasket between the housing and block.

Is this a known fault ? Any other suggestions as to what may be at fault ?

Thanks, Alex.

hi m8,if not ring seal has the engine got a bit back pressure? make sure the engine breather filter has been changed!!!