Do CEL code clear by themself?

[wawa]

Hello all

CEL appear (2000 S), stop at indy to have it check. He told me it's O2sensor related without telling me exactly what code. He did not had time to invest about it and I had to go back Home 300km away. Back Home CEL is still on and stay for 2-3 rides. Then I connect my actron to read them, P1126, P1133. I did not erase them, but at the next ride, CEL is off.

Could it clear by itself?

Thanks
Chris