So recently my car's been throwing a CEL/SES light and as usual I just take out my scanner and read the code. The first time it was a p0420 concerning catalytic efficiency. I ran over a speed bump and heard a scrape and I'm wondering if it dislodged an o2 sensor or created an exhaust leak. Regardless, after I cleared it once, it continues to come back. Whenever I scan it, it has two codes that say "n/a".

Any idea why it does that? I'll be crawling under the car tomorrow to check for exhaust leaks, etc.

Thanks!