Hello. I have a 2002 corolla with 200k miles on it. It’s most definitely the best car I've ever owned and I really don’t want to give it up. The only issue is I have a check engine light code for EVAP p0440, 41, & 46; I’ve had these codes ever since I bought the car 5 years ago. I did everything to fix the EVAP: new charcoal canister, new purge valve, new oxygen sensors, an OEM gas cap from the dealer, I even ran a smoke test with a smoke machine and found no leaks. I also used to have a p0420 code, I went to a couple of shops and they told me straight out that I need a new cat without doing any testing or diagnostic; one mechanic told me 9 times out of 10 - p0420 code means cat needs replacement. However last year my roommate had me add a gallon of lacquer thinner to the gas tank a couple of times and ever since the 420 vanished and never came back.

I was able to get my car smogged before by setting the catalyst ready on a lucky day since in California you can pass smog with pending evap. However this time, i just can’t get the catalyst to set ready. I’ve tried specific drive cycles bunches of times, I tried doing the 3000 rpm test for 3 minutes, I tried driving it around for 4 hrs straight without stopping.. It just won’t set ready. 

Is it possible that the EVAP code is preventing the catalyst from setting to ready? I’ve read this in a few places and according to some mechanics.

We have a BAR program here that will pay 80% of cost for emission-related repairs. A local shop quoted me and I would still have to pay about  $400 for diagnostic +  20% of repair. I’m considering doing this, but i don’t know if it would be worth it if at the end of the day, i clear the EVAP code but the catalyst still does not set to ready which means i sunk $400 for nothing. I suspect that I may need a new cat regardless of EVAP which is not worth it since they run for $1000 here in California. My registration just expired last month.