Hi all, few days ago my car gave me p0420 code and i cleared it and it came back after 500km of driving. So i looked online and found a video on youtube from using 1 Gallon of pure lacquer thinner in 1/2 tank of gas and driving the car for 200-250 miles. Has one tried this, i would really like a cheap fix before i drop 1k$ on new cat. On the other hand, i do have rattling noise (like lose heat shield) at engine start and when slowing down for stop sign and accelerating from 1st to 2nd. I have checked under car several times but couldn't find any lose shields, so is the catalyst making that rattling noise? Any help would be appreciated.
Thanks

 

Don't waste your time and energy; buy the new cat.

 

I would buy the new cat. I've looked into that method out of curiosity. That method is sketchy to me.

 

 

Stop being cheap.

 

That sounds like a great way to fuck up your fuel injectors and engine too

 

Mileage on the car?
Have o2 sensors been replace?

 

i just bought it 3 months ago and it has 108k miles. No i don't think sensors has been replaced.

 

This made me LOL. Thank you!

 

I had this error show on Saturday 09/02/17...this is the first time I ever saw P0420 my 07 RL. I refueled at a Circle K and about 10 miles later I saw a check emissions system message appear on the display and found P0420 code. The CEL was lit for about 3 days... Google consensus didn't think it was bad fuel but I drove it around and refueled at 1/4 tank... the CEL went out after 35 miles and 3 short trips. I checked for the code and it was gone. So far it's been 3 days and the code hasn't reappeared. Did you rule out bad fuel? I'm almost certain that Circke K gas caused my issue.

 

That Scotty Kilmer guys cracks me up. He's a pretty eccentric guy. Look up his video about Mercedes. Made me LoL. Literally. It's all true though....

I know that cleaning O2 sensors is typically seen as useless, but it might not hurt to give it a try. There's a gasoline soak method that might help, if you've got deposits blocking the sensor. I don't think I'd put anything in the tank that wasn't specifically shown to be safe for the injectors and fuel system.