02 Concorde- 02 oxygen sensor replaced, check engine light came back on
 

I went and had the Concorde scanned before changing the 02, bank 2, sensor 2 and it claimed to be the only issue. The other day the car took a few seconds longer to start and immediately after the car had started, the check engine light popped up yet again. The car had only 60-65 miles since the oxygen sensor was changed.

Why is this popping up yet again?

what are the codes?

The garage at the time of the oxygen sensor being changed said po440, po442 were 'pending'. I know that those both mean a small leak in the emissions and also bad gas cap. We changed the gas cap with a locking one a year ago. Though it's a bit weird that we had the car scanned the same day as the garage and it showed up at as only the oxygen sensor as the check engine light being the issue.

How is it possible that 2 scans within hours of each other end up with 2 different results as the garage showed up more issues?

mo idea