MotorKote Catalytic and Exhaust Treatment | 16 oz., Single

Used this on several of my cars with the P0420 code. It worked almost every single time, just follow the directions and don't fill up your gas tank until you are close to empty.This wont fix mechanical problems; but it's probably the best chemical cleaner out there for cats that doesn't involve taking them off and washing them.EDIT:Where I live the smog requirements changed for classic vehicles. I was now forced to register my 1991 Hardbody truck with a smog check. I take very good care of it, but since the car has past the 200k mile point and nissian is known for making shitty catalytic converters; I gave this another shot.Truck passed with flying colors. Not sure what is in this stuff; but the people making it sure as hell know what they are doing.I'm also not sure how the 100% guarantee works. This can't fix mechanical problems; so if it doesn't work your vehicle has a mechanical problem.

Worked perfectly, 2010 F150 5.4 with 244,000 miles. Yes, replaces the engine 20,000 ago but the exhaust system, including O2 sensors are all original. I’ve tried other cleaners with no success. Decided to try this, and because the truck had a 32 gallon tank, I purchased the 6 bottle deal. (Instructions say 1 bottle per 16 gal gas)1st tank had 3/4 of a tank when I added the first 2 bottles.2nd tank, added 2 bottles when I filled up.3rd tank, added last 2 bottles when I filled up.Gas gauge hit 3/4 of a tank and the check engine light went off.Reminder, I HAD 244,000 miles of build up on stock exhaust parts, including sensors.Worked so good, I’m buying another 6 pac for the truck to add again. First 6 cleaned enough to stop the engine light BUT I doubt it cleaned them completely. Figure I should continue what’s working.Really really works for check engine light due to 2 separate O2 sensors faulting.

My 2006 Honda Insight was running very rough and missing. I had it looked at at the local garage, and they hooked up the analyzer and it said that the catalytic convertor seemed bad, and also the oxygen sensors.After running most of the cleaner through it, it seems to be running much better. I had never heard of a catalytic cleaner. Hope that takes care of it, as the Insight is the most economical running car that I have ever had. It has 220,000 + miles on it now, with 57+ mpg lifetime. I bought it with 104,000 miles on it with 56 mpg lifetime. So, it has been making over 58 mpg since I have owned it. I knew that a new catalytic convertor would be expensive, but found that the oxygen sensors were even more expensive. So, crossing my fingers that this takes care of it lol

No difference after use in 2 vehicles. I've read positive reviews so maybe it's just a high mileage MOPAR thing which tends to be sometimes or maybe it just needs to be used a few times in a row to get results which I haven't tried. Will try a 2nd treatment on my Grand Cherokee to be sureI used it years ago on my old Durango and my check engine light went out but no such results this timeHeard some old men saying a 5oz 50:50 mixture of Marvel Mystery Oil and Lucas fuel injector will do the job. It did !!! The mixture completely cleaned the entire fuel system on my old 4x4 Durango. It runs better than it has in years using the mixture. I'm blown away at how much more power it has now

I rather expected no results and got no results. CEL light remains on. No noticeable change in performance. Followed directions. I understand these products do not work in all situations but I'm going to try a few other brands before making a decision on replacing catalytic converter. I did add a bottle of something else purchased from a retail store and it seems like some improvement in pickup, though it's also not doing anything for the CEL - don't expect any of them to work but overall worth a try.

This stuff works where other products have not.

For the last year I've had a check engine light along with a P0420 dtc code that was preventing me from passing a recent SMOG inspection. Before replacing the catalytic converter I decided to try a bottle of this first. A few days after pouring a bottle into my gas tank the check engine light went away and stayed off until the readiness monitors reset and i was able to get it retested. Today it passed smog inspection! So although I was highly skeptical this would work for me, I recommend trying this before doing any expensive repairs on your vehicle.

I purchased 2 bottles of the Motorkote MK-10351 for my 2003 Honda Accord. Sadly, this did not work. My mechanic at Honda told me if the Catalytic Converter needs replacing, there is no quick fix for it, other than to replace it. I will admit (may be mental), it did feel like my vehicle had more pick-up though. I may get a bottle for my 2013 Honda Pilot. He did say it's a great additive to add to keep the converter from failing quickly.