First, talk to your boss. If that doesn't work, get a new job or blow the whistle, or both. If your boss is trying to cover up a problem, then you will either become part of the cover-up, or you will appear to be part of it. You could even become the fall guy, the person who is blamed. In any case, your reputation will be damaged and you will suffer serious repercussions. Reveal the cover-up and/or get out.