I have a Whirlpool cooker hood extractor fan thingy which has a grease & carbon filter inside. We initially replaced it with a new one costing £12 from B&Q and now it's full of grease and needs replacing again.
I am just wondering, can I wash it with washing up liquid/detergent or do these have to be replaced?
You can't wash it, it will need replacing. Before going to B&Q though, I'd try a local independent retailer or a 'Euronics' dealer (local phone directory/yell.com.) as there will most probably be a non-Branded version available for a fraction of the cost