Liqui Moly8931 Catalytic-System Cleaner, uncoloured

Good material, works as described!

2003 Camry with CEL, could not pass emissions test. Used this product as advertised, CEL went away, passed emissions test and all is good. Well worth the cost.

very good

I'm generally very skeptical of automotive additives and research everything to death. The general consensus on catalytic cleaners was that they don't work. My 2017 Expedition threw a code for P0430, which indicates the Bank 2 catalytic converter is not functioning properly. Swapping in a new O2 sensor did not work. My next option was to replace the catalytic converter.On a lark, I decided to try this product. I figured if it didn't work, I was only out $16. I have software that reads information from the vehicle, so I can see what numbers the catalytic converters were generating on each side. Surprisingly, after one application, the numbers improved enough for me to pass my emissions test. I was prepared to be told it failed because I was unsure what the threshold for passing was. But instead it passed and the check engine light has stayed off for the past several hundred miles. I deducted one star because Liquid Moly has another very similar product that is added to the gas tank, while product this must be sprayed into the air intake. I accidentally purchased that other product first because the product packaging is too similar and use instructions can be confusing.

This does not go into your gas tank, you must buy a special pressurized sprayer to make this work. Then you have to know where to put it. For a person that's not much of a car guy buying a special sprayer and then finding someone with the same car that I have that has made a video and showing how to use this and then actually doing it is not going to happen when I can buy a product that I can dump into the gas tank. I bought some Lucas fuel additive and used it instead. I don't know if it was coincedence or not, but the check engine light went off. The most frustrating thing is this PERFECTLY SEELED NEVER OPENED PRODUCT CAN NOT BE RETURNED!!!!! So be aware you are paying more for this product, then you have to spend more time to use it, then you have to spend even more on special equipment to use it, and if things don't go right there is no returning it. I feel they should make this more clear. I'm literally just going to throw mine in the trash and take the $20 loss. Personally I would prefer if Amazon required a HUGE NO RETURN label on these type of products.

I was hoping this would help clear a partially clogged catalytic converter that kept setting off codes in my Chevy Malibu. After reading the application instructions and viewing an application video, I realized this is intended for race cars - or at least that’s what they showed, and requires as specialized mixing bottle to atomize the material before getting sucked in through a vacuum port. One source on the Mfg’s web site said you could put it in a spray bottle and apply a fine atomized mist through the throttle body intake of a vehicle. I attempted that with limited success (having to disconnect my Mass Air Flow sensor - before starting the car - and spraying it into the air intake housing). I tried to rev the engine while spraying the contents into the air intake, but I think most of the content just puddled somewhere. I was hoping for some sign of it working while spraying but didn’t see any. Then I buttoned everything back up and took the car for a ride and produced a HUGE black cloud of exhaust in the first 50 feet of travel. I then heavily accelerated hoping to push all the cleaner through the system but think it was a quick one-shot deal at the beginning only.It may have done some good because my trouble code hasn’t returned yet, but it usually takes several weeks of driving to see it return after clearing.I doubt I properly applied the product, but also don’t think it is reasonable for the average Joe to be able to properly apply this product, so am not scoring it very highly in this review. Maybe someone else could get much better results.

My daughter owns a 2012 Nissan Xterra. When it had about 175,000 miles it threw a P0420 code indicating a failing cat. Our mechanic quoted $3,600 to replace all 4 cats.That wasn't happening. I stumbled upon this Liqui Moly Catalytic System Cleaner and figured even if it doesn't work well, I'm only out $16. I powered the cleaner into the gas tank instead of spraying it into the intake as recommended.I cleared the CEL and tried the cleaner. The code did not come back on. She or I put a can into the gas take once every 3 or 4 months. We have been using it for the last 20,000 miles and over 18 months. Still running the original cats. I think we've put the cleaner in maybe 5 times since the CEL first came on. $90 over the last 18 months is definitely better than spending a few grand for new that will probably only last a few years.

Used in a 2012 Prius with almost 300,000 miles, the cat below threshold DTC light was coming on. I put this through the hose from the valve cover before the throttle body with a small pump up sprayer I got at the hardware store, while it did look like it was cleaning gunk out of the cat it did not solve the problem, the light continued to come back on with the same error code. I took the car to Toyota and they are in the process of installing the 2 new cats they said it needed, about $2,500 here in California. I also used it in a 2003 Chevrolet Tracker 2.0L with about 85,000 miles and no CEL. I was able to use some clear tubing to hook it up to a plugged vacuum fitting after the throttle body, I did not see anything coming out of the exhaust but the car seems to have better acceleration. I bought 3 bottles and poured all 3 in the sprayer. Still have some left for next time. Seems like a good product though not always a cure all.