How do Check Engine codes clear?

I've been having a P0446 code check engine light hang with me for a while. I've tried the new gas cap and new vacuum lines. Both times I disconnected the battery for a bit and the check engine light came back on within the first drive (pretty sure first drive? definitely wasn't gone long). I did have to reset my clock and stereo so I figured I should've given enough time to clear the codes/memory as well. I recently replaced my UCA's and had my battery removed for about and hour. Once everything was back together the check engine light was off. I've driven the truck close to 700 miles now. Probably fired it up at least 20-30 times since. Check engine light still off. So I guess my question is did I just not give the ECU enough time to clear its memory when I did both of those fixes? Would really love to believe this code is gone.

 

EVAP codes take the longest to set/reset. If you cleared it, I've heard of cases where it can take up to a couple thousand miles to reset. Highway miles are best.

 

Depends your bit might have not been long enough ! I saw any time between 30 seconds and 10 minutes go figure

Time to get a simple code reader that will clear the PO codes easier then disconnecting the battery.

For me anyhow.

 

I feel your disdain for the EVAP codes. So many vacuum lines and possibilities to chase down. If it's gone - just ignore it for now