Mary C. Lucking—January 13, 2026✓ Verified purchase
Inspection on my car due the end of January! My check engine light was coming on so I checked with a code reader & found it was a P0420. Read about the Catalytic Converter System possibly being in need of replacement or perhaps clogged. I am a woman, and know next to ZERO about cars, but I can read. Did investigate and found that the replacement of a Catalytic Converter system is mad expensive- also found this Moly Cleaner to add to gas tank. I'm not going to lie; I was nervous as I have a Kia Rio 2014 that has a very small gas tank and gets great gas mileage. In reading the consensus seemed to be to add to 1/4 tank of gas and drive fast for good periods of time to blow out the clog (if it was a clog). Did I mention I live in NYC and driving for long periods of time at high speeds can be a problem because of terrible traffic. Anyhow, this Saturday I poured the can into my 1/2 filled tank and hit a parkway near my home early morning. I did drive for 45 miles sometimes at 80mph then 60mph but tried to do it for a good few minutes at a time without getting pulled over. Checked my reader again, and it was not quite ready but the engine light did stay off. Next day, drove to work, stuck in traffic somewhat & never made it over 20mph & checked my reader again- all good to go for inspection. Went last night- my car PASSED and got that sticker in my window- so I am good for another year. The BEST money I have spent all year. Thank you for carrying this product! Saved me thousands! DONT HESITATE TO USE THIS. The hardest part for me was removing the cap on the can! Read more
Yunielkys Martínez—March 6, 2026✓ Verified purchase
Liqui Moly Catalytic System Cleaner removes deposits from the catalytic converter and fuel system, improving engine performance and reducing emissions. 🚗 Read more
Nemecio Ramos—February 23, 2026✓ Verified purchase
2004 Honda CRV failed the emissions test. It had a P0420 code which could be a faulty catalytic converter or failed oxygen sensor. We did not want to spend a lot of money on it because it is an older vehicle and might not be a long term vehicle for us at this point. I let the gas get down to about 1/4 tank. Poured this bottle of Liqui Moly magic potion elixir right here and filled up the tank with premium gas. Drove it around for a couple days. Took it back to the emissions test and BAM! Passed with flying colors. Just like that! A shop would've probably made us buy a whole new catalytic converter for $2.3 Million. No Sir, Not ME. Read more
Mike—September 14, 2025✓ Verified purchase
2019 Ford F150-I bought this product with a 1/2 tank of premium gas in my truck. I had an emissions light on that I was told by my mechanic was catalytic converter related. Shortly after I poured the product in my tank (maybe 40 miles),the trouble light went off. The trouble icon stayed off for the next 100 miles but then came on again. After another 200 miles the trouble icon went off again and has stayed off so far about 1,500 miles later using regular gas. Read more
Alvin—September 15, 2025✓ Verified purchase
Excellent item. The oiast time that I bought this, I was able to last a year before my engine trouble code turned on again for bad catalytic converter (which is expensive to replace and install). Liqui-Moly cleaned it efficiently and I was surprised by how long I was able to go before the check engine light went on again after using this at half-tank. I even passed my smog check. This is the second time I am purchasing (exactly a year later) and I am waiting to see how long I can go this time for my Acura TSX 2012. Combining this with a year's worth of 91 octane fuel will certainly allow my car to run clean and efficiently with no problems. Read more
Customer—March 15, 2026✓ Verified purchase
It didn't work for my Kia Sorrento so I can't give a good review. Read more
Dennis Epler—January 18, 2026✓ Verified purchase
This stuff actually worked! We put it in our 2014 Silverado 1500 with 200k + miles. It took about 2 weeks of driving though. Probably 2 tanks of gas. Check engine light went out. We had a catalyst code for a month or so before using this stuff. Read more
Peter—March 7, 2026✓ Verified purchase
I bought it for a check engine due to catalytic converter but it do nothing, the problem still exists buy it as an injection cleaner. Read more