Rislone 4720 Cat Complete Fuel, Exhaust, Emissions System Cleaner, 1-Pack

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.

Worked for me! Believe me my tags renewal was approaching and I was stressing. Simply follow the directions. After the initial drive on a 1/4 tank of gas I filled up and drove about 15 miles a day until below 1/4 tank. My engine light didn't go off, but after filling up again and driving another 15 miles it still didn't go off. The second day I went to burn another 15 miles the light was off! Went immediately down to the emissions station, I was nervous but SHE PASSED! I been walking around with a smile all day.

I was looking at close to 600 in repair costs for a new catalytic converter and install. After doing some research, I found that this is the best product IF you use it soon after the check engine light comes on. I used it as instructed and about half way through the filled tank the light went off and I passed inspection. Couldn’t be happier. Definitely recommend. Make sure to not let too much time go by. Use this asap and make sure you drive like you stole something when you first empty the container in your tanks for at least 30-40 miles before filling up. Follow those instructions!! Best of luck.

It did turn off my check engine light for my catalytic converter until my next fill up. Didn't work again.

Useless product i put this in my gas tank and noticed zero difference. I bought two bottles, but because of their ridiculous 'no returns or exchanges' rule, I am stuck with the second one. What a rip-off and a waste of money.

Rarely leave reviews but this stuff worked for me! Vehicle renewal coming up and CEL had kicked on, it's been weird kicking on and off for a bit but always reading the same code and having no changes in performance/mileage but this time it had been on for a bit. Was getting worried with the renewal coming up so soon and tried this on a hail mary and it worked. I have a small tank (9.2 gal) so I'm wondering if the higher concentration helped in my case. I followed the directions to a T, added stuff to a half tank, did some good speed highway driving and then some in city start/stop for the 20-30 miles they recommend. I felt like going 30 is better because the concentration of cleaner/gas is higher at this stage so you're using that treated fuel. Then I filled the tank and drove roughly 30 more miles of mixed driving, got home light still on. Later went to grab some takeout, started car and light turned off! I turned car off, took wifes car to get the food and first thing this morning drove to the inspection place and passed I'd say follow the directions to a T but also lean towards whatever leaves a higher concentration of the cleaner. I also used Premium the entire time for everything. I had even filled a tank of premium before all this hoping it might clear. The car also seems to be running a little more quiet and smooth right now

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.

I am a 69 year old that drives a 2007 honda fit. 8 days ago my check engine light came on. I took my car to auto zone where my car was diagnosed with code P0420. My car has 136,000 miles I did not want to invest thousands on a fix. I have used Rislone products before and trusted the brand. I had just filled my tank so i had to wait to use the product. 2 days ago I used this item as directed. The check engine went off, before I even got home and has stayed off. I am very pleased and will update after a month or if the status changes. I recommend trying this first before replacing other costly parts. I am at 1/4 tank of gas and have just over 280 miles driven on this tank of gas.

I said I would write a follow up. Put in around Christmas see review. Have now put about three tanks of gas through pickup truck. No codes have come up since. So would say it well worth buying. I had all sorts sorts of codes showing up turning on eng light had to clear every 1/2 tank.

送ってきた商品が2020年製 廃棄処分品 完全にだまされた 箱は日焼け 潰れあり 最悪だ 金返せ

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

I had an engine light come on in my 3010 Honda Accord. OBD2 scanner said it was a catalytic converter issue. I put this into my gas tank when it was about half full. After a few days of driving, it fixed it and the light is off. I've done this once a year for 2 years and it keeps working. Love it as a cheap way to prolong the life of your old car!