Cataclean Fuel & Exhaust System Cleaner – Pass Emissions Tests – Clear Check Engine Lights – Restores Catalytic Converters, DPF Filters and Cleans Fuel Systems, 5L (120009CAT)

Just as advertised. 👍Although it didn't clear my check engine (P0420 code) light but I do feel a huge difference as far as my trucks horsepower. My truck runs smooth and picks up faster.

If you are facing a failed emissions test, don't give up on your catalytic converter until you try this. I recently failed my state inspection due to high NOx levels—my readings were hitting 700 PPM, which is well over the limit. After some digging, I realized my downstream O2 sensor was dirty and essentially unresponsive. How I Used It: I followed the "1/4 tank rule" for maximum concentration: Waited until my gas tank was at exactly 1/4 full. Poured the entire bottle of Cataclean in. Immediately hit the highway for a long-distance drive. Drove it hard until the gas light came on before refilling with fresh fuel. The Proof (OBD-II Data): I monitored the entire process using my BlueDriver Bluetooth OBD-II scanner. It was incredible to actually see the live data change. Over the course of that highway drive, the downstream O2 sensor readings began to stabilize and "wake up." The graph went from a flat, sluggish line to responsive, healthy signals. The Results: I went back for a re-test and passed with flying colors. My NOx dropped from that failing 700 PPM down to an average of 75 PPM. Final Verdict: This product isn't "magic in a bottle" for a physically broken or melted catalytic converter—if it’s dead, it’s dead. However, if your fuel and exhaust systems are just carbon-fouled or your sensors are too dirty to read correctly, this stuff is a lifesaver. It saved me from a $1,000+ repair bill. Highly recommended!

Here's the quick summary: Yes I used this and yes my car passed smog test.... but I would try lots of other things before using Cataclean again. My vehicle is a 2004 Toyota Sienna with 137,000 miles. Check engine light (CEL) has been on for two years now. The CEL is on due to the following codes P0420 - Cat Bank 1, P0430 - Cat Bank 2 , P2238 - AF Sensor Circuit. This year we got the registration renewal and were required to get a smog certificate. Since you can't pass smog test with CEL on, we took the van to the dealer to see about getting it the CEL fixed. The dealer recommended replacing both catalytic converters the A/F sensor and calibrate ECM. All for a cost of over $2,800. So instead of spending the $2,800 I figured it was worth it to give Cataclean a try. I followed the directions and added the entire contents to about 1/4 tank of gas. Then immediately drove the van until it was empty. The van was not completely empty, but the yellow fuel warning light did come on and the gauge was on E. At this point I filled up the tank with premium gasoline. After filling it I immediately drove the van for about 40 miles. I was expecting the CEL to turn off but it did not. At this point my story gets less normal than most I suppose. My wife drives this van most times and I have another car. It just so happened that my wife was sick with a bad case of the flu and she did not drive the Sienna for more than 1 week. So the Sienna sat with nearly a full tank of fuel and whatever was left of the Cataclean for 1 week. After 1 week of sitting in the garage, I decided it was time to try to drive the van and see if the CEL would turn off. This is where it gets very weird and discouraging and expensive. I pulled out of the garage and the van barely ran at all. It felt like only half of the engine was running. The engine had very little power and to make matters worse the CEL was now flashing ON and OFF. I pulled over and did some quick research on my phone and found out that a flashing CEL is bad news. I spent the next 4 hours "babying" my car. I would drive it for a little bit and the CEL would flash. So I would pull over and let it idle next to the curb. When the engine was simply idling the CEL would not flash. I did this for hours and hours and the CEL flashing got less and less prevalent. Finally the CEL stopped flashing after about 4 hours of driving and idling. If this does happen to you, you need to be very careful. Driving with a flashing CEL could lead to really expensive damage and even your car catching on fire. After that long evening of babying my car, the CEL never flashed again. But the car did not run correctly after that either. The car was rough at idle and vibrated a lot while it ran. And now, my car had a new code P0354. I took it to a mechanic and he replaced the #6 ignition coil and spark plug and cleaned the fuel injection system. This made the car run smooth and cleared the P0354 code. Replacing the ignition coil spark plug and cleaning the fuel injection system cost $510. I had a lot of expensive problems after I put in the Cataclean (see above). These problems could have been a coincidence and I could have had those problems without the Cataclean. After all, it's an old vehicle with lots of problems. Anything is possible. But I don't think I will be using Cataclean again. I cleared all codes and tried to run the monitors. For those of you not familiar, there are "monitors" which run in software on your vehicle. These monitors must be run and passed with no codes before you can have your car smogged. If the monitors generate codes, then the CEL turns ON. If you clear the codes, your CEL does go off, but your monitors are now "imcomplete" in your cars OBD memory. You cannot pass smog with incomplete monitors (actually the number of incomplete monitors allowed to pass smog varies from state to state so check with your motor vehicle department). You can find the rules for California here: [...] So now my car runs smoothly, the Cataclean has run through the emission system and the CEL is off. I have two incomplete monitors. One of the incomplete monitors is the Catalytic Converter monitor. So I then drive the van around town running some errands. Mostly stop and go, but some highway driving. After about 50 miles the CEL turns ON and generates code P0420... very discouraging. But I did not give up. I cleared the P0420 code and decided to try nothing but highway driving at moderate speed. Just a hunch I guess. So I got on the freeway and drove. Entirely freeway driving at very moderate speed. I got in the slow lane with the trucks and probably averaged 55 MPH and for it's worth I turned my Air Conditioning off. I did this for about 75 miles. I kept checking the scanner to see if the monitor for the Catalytic Converter had run, but it said incomplete. I must have checked the scanner 30 times to see if the monitor had run. Then it happened, the Catalytic Converter monitor ran and the status went to OK with no code. As soon as the monitor ran with no code I found the first smog station I could find and got a smog certificate. YEAH!!!! In order to do all of this I needed an OBDII scanner with me in the car to check monitors, read codes and clear codes. I used a very inexpensive OBDII scanner that I bought at Wal-Mart for $21. I think some of the inexpensive models offered on Amazon would work as well. You don't need an expensive scanner to do this. The main thing for checking monitors is a feature called "I/M Readiness Status"-- make sure your scanner can do this function. So did the Cataclean help pass smog? Did Cataclean cause the damage to the ignition coil? Did not driving it for a week in the middle of this process cause a problem? .... I don't know. If I were to ever need to use Cataclean again, I would drive the vehicle... a lot and try to get it through the system as quickly as I could. Hopefully, I won't need to use it again.

Purchased this product out of sheer desperation and it actually worked! My 2010 Jeep had the O2 and Cat lights stuck on the drive cycle and it wouldn't clear smog. Drove that sucker a thousand miles over two-months at varying speeds and the drive cycle just wouldn't clear. Added the Cataclean on a quarter tank and drove for about 40 miles and the O2 light cleared. Filled the tank and drove normally for about half a tank and the Cat light cleared. Breezed through the smog check on the first try and now I am good for two-years. I almost didn't buy this product because it seemed too good to be true but it worked for me. Hopefully it will work for you!

Works great! Was told I’d need to replace my cat for $3k used this and my check engine light went off and has not returned (4 months). I’ll probably still have to get it done but I can take some more time.

I'll try to make this brief. I used Cataclean once about a year ago on recommendation from a mechanic and various online sources as a stop-gap measure to keep the engine light off for enough miles to pass inspection with a P420 catalytic converter code. This also required turning off the light with an OBD scanner first, adding the Cataclean, then driving over 100 miles and resetting the I/Ms. It was successful, but I can't say if the product helped keep the CEL off or if it just happened to work out. After inspection, the CEL returned at 280 miles, which it always will, this is not a permanent fix, please understand that. Now comes the very, very bad part. This year, each time I turned off the CEL to see how long it would remain off before inspection, it came back on well before 50 miles. So I know my catalytic converter is getting worse, no way to make it one more year, it would have to be replaced. But I thought I'll give Cataclean one more try and maybe it will help keep the CEL off a bit longer before I commit to $2,000+. Cleared the code last night. Added the Cataclean, precisely as directed, 1/4 tank, etc. Started driving. Within ONE mile, massive misfires, chugging, struggling, no pickup, CEL FLASHING. I had entered a highway on ramp when it hit, managed to get up to speed at least, then exited immediately. Vehicle shaking and sputtering at stops, I put it into neutral and gave it some gas so it wouldn't stall. Drove to the nearest gas station and filled the tank to at least dilute this garbage, the best option at the time. I ran my OBD scan at the gas station, P0300 random misfires code, all cylinders reporting misfires. Cleared the code so I could see how fast it would return. I drove only around my neighborhood so I wouldn't be far from home if catastrophe struck. The CEL of course came on again in a few miles but the jerking, stuttering, shaking and struggling were greatly diminished now because I diluted the additive with premium. The problem remains, however. When the CEL came on again, at the very least it was steady and not flashing, certainly because of my quick thinking to dilute it. Now I'm in the unenviable position of HOPING it's JUST the catalytic converter that got badly clogged from the release of filth or whatever the product released into the system in the single mile I drove it after adding it to the tank. Did the research online. It could be a lot of system components affected in addition to the already weak cat. Look it up yourselves, PLEASE! This can foul your spark plugs, fuel injectors, O2 sensors. It can severely damage your cat when you have misfires, causing it to overheat and break apart. There are tons of articles about all the possible side effects of using this. I never came across them when I researched it the first time because I didn't specifically search for these side effects. All I saw were opinions that maybe it will work out, maybe it won't, but that it was safe. THIS IS NOT A SAFE PRODUCT! Look, maybe it's OK for some people - it doesn't work at all for others. A very mildly dirty cat might be cleaned enough to get through an inspection and turn off the CEL for a while longer than normal but - wow. Did I ever make a huge error using this again. Yes, nothing happened the first time I tried it. You might get lucky. You also might release so much gunk into your engine and exhaust that you destroy your vehicle to the tune of THOUSANDS. Do the research. Be smart. I poured this junk into my tank without a care in the world, thinking it would either help keep the CEL off or not and that would be it, never suspecting massive misfires and a flashing CEL. It's a holiday weekend now and I can't get to a garage until Monday. I will update this review when I learn the extent of the damage and I'm hoping it's only 2K for cat replacement. Imagine that. Think long and hard about trying this. I hope I can save some of you from the scary situation of being on the highway and misfiring and struggling to get up to cruising speed and a nerve-wracking drive back home or having to call for a tow. Consider this a public service. Get online, find out everything about this and other additives before using them!

Item was great , took 10 days to get it delivered. So much for paying prime .

I recently utilized the Cataclean Fuel & Exhaust System Cleaner, and it has demonstrated exceptional efficacy in addressing several automotive maintenance concerns. This 16-ounce liquid formulation, produced by Mr. Gasket Co., is designed to reduce carbon accumulation in critical components such as catalytic converters, oxygen sensors, fuel injectors, and cylinder heads. Following a single application, I observed a noticeable improvement in engine drivability, including smoother idling, reduced hesitation, and enhanced fuel efficiency, which aligns with the product's claims of potential hydrocarbon emission reductions by up to 50 percent. The product's compatibility with gasoline, diesel, hybrid, and flex-fuel vehicles, without altering fuel composition, ensures broad applicability across various engine types. Its patented, EPA-approved composition is non-toxic and unscented, facilitating straightforward usage—simply pour into the fuel tank every three months for optimal results. Notably, it assisted in clearing a persistent check engine light and supported successful emissions testing, thereby extending the operational lifespan of exhaust system elements like DPF filters. In terms of construction, the durable COEX-HDPE bottle with a long-nose design accommodates capless gas tanks efficiently, enhancing user convenience. Overall, this cleaner represents a reliable, cost-effective investment for maintaining vehicle performance and regulatory compliance. I recommend it to automotive professionals and enthusiasts seeking a proven method to restore and preserve engine integrity.