P0420 code after filling gas tank

[Fat Slob]

For the last 3 times I have filled up, as soon as I start my Expy I get a check engine light, and when I get home I scan it and get code P0420 Catalyst system Bank 1(dont remember exactly what it says). I ONLY get the CEL light after I fill up, it doesnt happen any other time.

I just replaced all the coil packs and installed new plugs this past summer, and also had the drivers side CATS replaced this summer also Which side is Bank 1? Drivers or Passengers? Thank you!

Try a new gas cap.

 

[Underdog66]

I have this same issue. Any resolution to the problem?

 

[JUST4FUN]

Never try to put more gas in after the first time the pump shuts off It will wreck the evap system

 

[rjdelp7]

Update. In 2021, I started getting a P0430. It was the other bank. Both front Cats had small rust holes, near the seam. Interestingly, the whole rest of the pipe looked fine. I ordered both sides (all 4 converters) from Canada(ebay). $540. It cost $325 to get them installed. However, I sold the old, scrap ones on Ebay. They got bid up to $900. Apparently, early 2000s Ford vehicle have high Palidum

 

[Underdog66]

Update.
I was able to resolve this issue with a bottle of CataClean for less than 30 bucks. No more CEL code P0420. Also my fuel millage increased from 12 MPG to 15 MPG. I highly recommend this product to anyone with catalytic converter issues.