I had an old post regarding the replacement of the engine air filter on my 2013 ACE 30.1 V10 engine. Look down the post attached and check the pictures and diagrams for the notches in the rear lid of the air box. It might also apply to other coaches. Once you release the front clamps you have to slightly lift and push the air box lid straight back hard to release the rear as I recall. Once you replace the air filter make sure you properly replace the air box lid at the rear first to make a proper seal.
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