p0420

Hey Y'all, Skimmed the threads I only seen like one other person having the same issue with their 2017 Buick Encore. The check engine light keeps popping up. Last year I noticed the car stalling when idle, and struggling to start when I would refuel. Took it to a GMC dealership and they...

Recently had repairs done on my 2002 Buick LeSabre. After a few days, the check engine light came on again. Didn’t think much of it until the car started jerking while accelerating, it had a rough idle and eventually started having stalling problems. I lose power steering and the “VOLT” light...

Hello, I have a 2013 buick encore with 80,000 miles, basically brand new, but a code P0420 has been bothering me for the last few months. It drives perfectly and mpg has been the same but now it's time to get the dumb texas State inspection so I have to get rid of it. I've removed the catalytic...

I keep getting a P0420 code on my 2013 Buick Encore. I’ve replaced the CAT— replaced 02 sensors, replaced spark plugs. Cylinder 1 had a misfire, replaced that too. Now today—same code! Any advice??? I’ve put so much money into it I don’t know what else to do and neither does my Mechanic.

My lacrosse has about 107,000 miles. I had no problems until a month after I had my spark plugs changed. I would get code P0420 I reset it and it wouldn't come on until about 600 miles later this happened twice. So in between the first and the last time i used cataclean to see if that would...

Hey All, 1996 Roadmaster Wagon with the LT1 Engine (multi port injection) is throwing code P0420. I had the code pulled and the description is "catalyst system efficeny below threshold bank 1." This code came up a couple months back when I had a fuel pump failure. However I had it cleared...