4720 Cat Complete Fuel, Exhaust and Emissions System Cleaner, 16.9 oz, 3-Pack

Kept resetting P0420 CEL on my 2007 Toyota Corolla, hoping I could quickly go through drive cycle and pass my smog check before it came back on. Same code kept coming back on within 2-3 miles of a reset so using Rislone was my last hope before I tried the non fouler trick. Below is exactly what I did, hope it helps someone! 1) Filled my gas tank with premium gas, drove it down to half tank over a few days of driving before I inserted Rislone. 2) Drove ~30 miles and then refueled to full tank with premium gas again(Half highway/half city as instructions state) 3) Instructions say after completing step 2, drive the car to 1/4 gas tank at which point CEL should clear. For me, I drove ~25-30 miles over 3 days, clearing the CEL each time it came back on. During the 3rd day (~60 miles since using Rislone), the CEL didn’t come back on and all monitors reset! Immediately went to smog station and passed. CEL is still off, not sure it will last but who cares! Car is running fine and I don’t need to pay for a new converter just to pass a smog test! Tips: 1) Not sure if premium gas made a difference but I read several people say they used non ethanol/premium gas which cleared P0420 so figured it couldn’t hurt. 2) I bought a cheap OB2 monitor which I kept on when driving so I could see exactly when CEL was coming back on and when monitors are smog ready. If you’re lucky, resetting CEL and going thru drive cycle may be enough to get past smog without using Rislone. In my case, the P0420 CEL would come on within 2-3 miles each time I reset the CEL so using Rislone was a must. 3) Each car is different but generally speaking, once you reset CEL the drive cycle consists of warming up the car for a few minutes and driving 50-60 mph a few times, ideally letting the car come to a stop with no or minimal use of the brake. Make sure A/C is off. Using the OB2 monitor while driving the car will help you get a feel for your cars drive cycle. 4) If a CEL code is pending, the relative monitor to your code will not clear! In California, all monitors except EVAP have to be ready to pass smog, your state may be different.

Has worked for me in multiple vehicles with O2 sensor issues. Make sure you only have 3/4 tank and drive at highway speed and beyond for 15 miles. I've watched the check engine light go off while driving or shortly after restarting

2011 gmc acadia and have been fighting a P0420 Low efficiency bank 1 code for about a year or so. I've tried cataclean with inconclusive results only because I've done other things at the same time and code has cleared. Oddly enough changing the oil usually cleared the code but eventually came back. I've taken intake apart and, anyone who's owned an acadia, knows the poor fuel system design in the fact that oil gets into the intake and pools up. Along with changing PCV valves and modifying them, I've got the code to go away multiple times but this time, was not going away. I did the oil, cleaned intake, changed air filter etc., etc. Stumbled on to Rislone and it has some pretty positive reviews. I'm a believer in fuel additives and fuel system cleaners but I'm a little skeptical on stuff like this. As stated, I've used Cataclean before and other Cat cleaners with no luck. So, outta desperation, I got myself a bottle and followed directions....Dumped full bottle in when tank was 1/2 full. Drove to my destination about 25 minutes away, mostly highway/high speed roads. It was a 16 mile drive, check engine light was still on when I shut the car off. Did what I had to do, started car 10 minutes later and low and behold light was off!! I couldn't believe it. Drove another 10 miles or so, filled up per the directions and drove home. If I think about I'll update this post down the road but I'm impressed!! UPDATE - CEL came on again after 8 days. Do it works but then doesn't??? I dunno.

It seems to be working but you never know. Value for the money. Easy to use, just pour into the tank

Product does not work as described. Check engine light still illuminated while using the product. I tried to return thru Amazon saying the product did not work/defective and was told it was not eligible. There is a money back guarantee on the box, I filled out the form and submitted it, wait and see if they approve it.

I don't know why it didn't work on my car. I used two bottles. Maybe I needed more. But I didn't continue. I gave up. But I heard from my friend that it worked for him.

appears to be good stuff can't really tell but put it in truck and hope it cleans up some engine things

Had a warning light that the Cadillac converter was bad put a bottle in a half a tank of gas 450 miles later the light went off

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Best !! Engine light is gone now. It’s a been a week and I am not seeing the Engine light anymore 😊

Does not work for me, and no guarantee as the described