How do I fix error codes?

All error codes are listed in the back of the Operating Manual, though the most common error codes are listed below:
Error 1: Dirty filter; change the filter that the machine is telling you is dirty.
Error 2: Pre-filter safety pin is not fully inserted into engagement hole. Make sure pre-filter pin is fully inserted.
Error 3: HEPA filter fault; remove hose and make sure HEPA filter is not damaged.