I replaced catalytic converter in my 2014 Buick Encore. Bought converter on website Parts Geek. But still have the light on. It says: P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD BANK 1. What is going on?
You can't just replace the CAT to solve the problem. You have to find out what is happening with the engine to cause the CAT to show a DTC p0420 inefficiency code. Overly rich mixture, burning oil, vacuum leak, bad 02 sensor, etc.
It was previously diagnosed bad converter by dealership. {black}:shocked:
@bikun - If you believe anything the dealer tells you, you're in trouble. Here's how it works - The dealer tells you the CAT needs replacement for $1000. You get it done. A month later, the same code comes back. The dealer tells you your injectors are shot, so are your coil packs. Oh and by the way, these have ruined your new CAT which has to be replaced again, plus the other parts. Now it's a $3000 job on top of what you already spent. Are you getting the picture?
Have you performed any of the diagnostic steps to determine the actual cause of the P420 code? (There are several.)
Search the board regarding the lacquer thinner issue, it has been brought up here quite a few times.
I replaced catalytic converter
Was it welded in properly? Did you check for exhaust leaks?
Did you find out why the cat failed? Something is wrong with the engine if the cat lasted only 8 years.
I Heard about your theory/idea to add lacquer thinner to gas to get rid off the code P0420. My question is how much of the thinner add to gas ?