Strange Behavior for a Toto

Alright, I just remodeled my bathroom. Apart from adding a 3" drain for my shower, and a new 2" vent I did nothing else with the pipes. I put in a new Toto two piece pacifica. I love the toilet. It was working well, for about a week until it woke me at 4am this morning with a strange gurgling sound. I flipped the lid to see large air bubbles coming up into the bowl
I tried flushing the toilet but it only filled with water
slowly, the water subsided
I plunged it- gasp! but the only change was that it drained a little faster
Gone is the mighty flush
What happened?

Sounds like your sewer line is backing up. Toilets do not make air bubbles, like your describing, on their own.

toto

The toilet is in the basement. However, there is a check valve installed -about 30 feet away- in the waste line.
An additional note: The toilet went back into normal mode later on in the morning, but I'm still hearing intermittent gurgling noises and seeing air bubbles.
PS> the check valve was installed years ago for the very reason you mentioned- our street seems to have a problem with the main line which caused the prior owner's rec area to fill with...you can guess what.

Check valves often don't seal completely, especially after they get older and things get trappped in their sealing area. Yours could be leaking a little. Nothing to do with your toilet.