Has anyone tried clearing P0420 or P0430 (Catalyst System Efficiency below Threshold Bank 1 or 2) codes using 1 gallon of Lacquer Thinner to 9 gallons of gas? I'm thinking about trying this out on my 04 RX330 AWD after watching this Scotty's channel.

 

I know that lacquer thinner will harm certain plastics. Might not be worth finding out that it eats a seal in your fuel system.

 

+1 not risking it....

 

I really doubt that adding lacquer thinner should harm the car in the short run. If you compare the main ingredients to Berryman's B12 Chemtool and lacquer thinner, they are remarkably alike (Acetone, Toluene, Methanol), if not identical. I've used B12 Chemtool many times without any ill effects, although not quite as concentrated as suggested. I figure that a gallon of B-12 per half tank is approximately equivalent to a 15 oz can of B-12 per gallon of gas. Berryman's is only $3 a can. Lacquer thinner runs about $13-17 a gallon. Its seems like you could buy 4 cans of B-12 and put it in with a 1/4 tank of gas and have fairly good peace of mind.

 

Most likely not the best solution as a quick fix for your vehicle. I wouldn't risk it, maybe on a 1997 Chevrolet Cavalier.

 

I had watched the video that LSBen posted quite a while back, but never had a catalytic converter problem. So I decided to see what Scotty Kilmer's competitor, Eric The Car Guy, had to say about cleaning a catalytic converter. Amazingly (to me, anyway) Eric had seen Scotty Kilmer's video and made a video in response to it.

Spoiler alert: it didn't work. But Eric did not use a gallon of lacquer thinner, he used only a quart.

www.youtube.com/watch?v=ZlPadYU2mPg

Eric also did another video using sodium Hydroxide to clean the catalytic converter. Sodum hydroxide is used as a drain cleaner and oven cleaner, so it is pretty nasty stuff.

Spoiler alert: it didn't work.

www.youtube.com/watch?v=6qSMgj5_djE

 

Eric the Car Guy has some excellent advise on whatever I needed to do some research for so far, excellent videos without the nonsense most others seem to specialize at.
Cataclean has mixed reviews, although if your catalytic converter is defective there is no magic cure.

 

In most cases, P0420/P0430 is not a bad cat. There are several contributing factors that could cause that code to come up. Even a bad rear 02 sensor could be the cause.

Examples:
Fuel quality
Air intake quality
Spark/ignition system
Oil quality
PCV system issues
Rear 02 sensor

Nearly all mechanics will want to throw on a new cat, because none of them want to take the time to do real-time scans and dissect the information that OBD is providing for any hints of something not working as it should. The problem is, unless the root cause of the problem is found and corrected, it's going to happen again, and again, and again.

There was a great writeup on a Subaru forum I used to frequent. I'll see if I can find it and post a link for more information later today or tomorrow.

 

Agreed, even something as simple as a faulty Gas Cap could set off a Code, I had a vehicle which set off a P0420 Code, it disappeared after a long road (highway) trip, mostly likely residue in the system was cleaned out. Another vehicle, no P0420 code while driving in the city, it would set off as soon as I hit the highway, which was really weird. A lot of backyard mechanics swear they have the ultimate, this will not fail cure for the P0420 & P0430 Codes, off course the cures all vary & may not apply to your vehicle.
Looking forward to the Subaru write up, there has to be a step by step plan available somewhere to follow with a successful ending.

 

It took a little digging, but I finally found it. Let me know if you can't access the thread, and I'll copy and paste what I can into here.

http://www.subaruoutback.org/forums/...diagnosis.html

 

I tried the lacquer thinner and it really didn't work for me. At best, it might delay the code coming back for a while, much like any gas additive. Ultimately, O2 sensor spacers looks to be the best fix.

 

Has anyone ever used cataclean? Seems to have mixed reviews online

 

Having recently experienced a P0430 and P0420 type problem, I wouldn't try any additives or lacquer thinner. These types of problems are almost always due to:

1. Bad O2 sensor
2. Exhaust system leak
3. Clogged catalytic converter

Usually it's a bad O2 sensor - these things fail after a couple of years. I wouldn't let any shop talk you into replacing the entire catalytic converter, unless you have absolutely ruled out all options because of cost.