Rislone 4720 Cat Complete Fuel, Exhaust and Emissions System Cleaner,16.9 oz. | Cleans Catalytic Converter, Reduces Emissions & Saves Gas

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.

Not much else to say, there. I followed the directions to the letter (driving more highway AND city than what's instructed) and P0420 remains on the OBD.I've been told now by two very experienced mechanics that these products rarely work - after now trying both Cataclean and this one, I now understand why they say this.EDIT EDIT EDIT!!!Just changed to 5-star because, although it took driving the car beyond what the instructions say, it has worked perfectly. P0420 is now gone, vehicle passed state inspection "with flying colors" and registration is complete.Key take-away: Give this more time to work if it doesn't do the job right away. I did nothing different - same gas as always (I fill up with Chevron or Texaco almost every time as they include Techron in their gas and my former racecar driver brother-in-law says that's the best). I do also add a bottle of Techron on occasion to give an extra "boost" to the cleaning power.

This product works like it was made in freaking China. It didn’t do anything to my car. What a big waste of money I followed the directions specifically had no change. I do not recommend buying this product waste of money! And the worst part about it is they don’t even give you a refund if it doesn’t work so basically 100% chance of failing and not reimbursement !!!

I.was used to last year very good product! Thank you!😘😘,

I've been battling the dreaded P0420 code in my 2011 CR-V for months now and really did not want to spend the money on a new Catalytic converter. Bought this product, followed thje directions exactly and ... praise the Lord!.... passed the E-check! Good for another 2 years. Great product that actually does was it says!

P0420 2010 accord. I followed instructions adding it at a bit below half tank and drove about 40 miles at different speeds. CEL stayed on. I cleared the codes and drove about another 40 miles. When my readiness tests completed I got it inspected. Then the next day the CEL came back on. If I were in CA I wouldn't have passed since you have to drive 100 miles after resetting CEL. That's why 3 stars. I probably could have passed without it since my CEL comes on and off at times..

A code for my cat converter came up and a mechanic recommended a whole new cat, pricey. A friend of my dad who used this product to help older trucks pass emissions recommended this cleaner for our problem. I bought 3 bottles for a deep cleaning as instructed and used the last before emissions testing. Check Engine light was off (Colorado SMOG CHECK must have check engine light off) and passed SMOG Check comfortably. Helped keep my 05 Nissan Armada running for another two years. Worked for code we checked.

My check engine light was on.The mechanic said 1 of 4 catalytic converters was bad. $1100.00 repair.The description of this stuff said it might work.So I poured the bottle’s contents into my gas tank. Turned the key.The check engine light was off.It was night. The dash was darker than usual.I didn’t notice that the familiar orange light was off until a couple of miles down the road.I recommend this stuff.It worked. That light has not come back on again. I drive a 2004 Ford Crown Vic. The mileage is greater than 277,000.Try it.