Will running a can of Seafoam through the gas tank of my 2003 Camry 2.4l cause it to throw a P0420 code? I put a can in a fresh tank of gas 2days ago. Today,after a 200 mile trip, a check engine lite came up. OBD reader came up with a P0420 code. The car is running fine. Did I trash the cat ? BTW the car has 200k miles on it.

 

I would try running out that tank of gas and then disconnecting the batter overnight.
Maybe it just needs a reset?
I'd start with that before starting to do any work/or throw parts at it.

 

Thanks for the reply. I live in a county in Texas that does not require a smog check to pass inspection, so I'll run a couple of tanks of gas through it, reset the CEL and see what happens. If the CEL keeps coming on, I'll spend $100 for a cat just to keep it stock.

 

Sounds like a good plan.
Any news?

 

Well, apparently a full can of Seafoam in a tank of gas is too much for the o sensor to handle. I ran it down to half a tank, topped it off, ran it down a quarter of a tank and the CEL light went out. Lesson learned, sometimes too much of a good thing can be counter productive.

 

Sounds like it worked out!
Could've ben worse I guess.