P0420

[fowlken8]

Hello everyone,

So I now have P0420, catalyst system efficiency below threshold. My code reader can read live data and my O2 sensors are reading just fine during operation. I am not noticing any negative effects while driving. How do you test a catalytic converter? Anyone else had this code and know an easy way to troubleshoot? Is this common with manifold leaks? Check for a random hole in the exhaust?

Thanks

 

[08H3]

You can either fix it by replacing the converter, or you can just make the light go away for a lot less. Google "P0420 spark plug anti fouler".

 

[fowlken8]

I added something called Cataclean to the fuel tank while under 1/4 tank and the light hasn't come back. Am I crazy? Can a simple additive possibly work? Not even sure the Cat or O2 sensors effect shifting but everything feels smoother and RPMs are even more stable while driving. Feels a little more powerful too.

Placebo effect.

 

[650Hawk]

My Alpha started to occasionally give me the P0420. Started about once every other month. Progressed to once or twice a month. Eventually, it would come back as soon as it went through a drive-cycle, every time. Cats are expensive and I needed a smog check, so I figured I'd try the "anti-fouler" trick. That was about 6 months ago; haven't seen the CEL since!:cheers:

 

[fowlken8]

My Alpha started to occasionally give me the P0420. Started about once every other month. Progressed to once or twice a month. Eventually, it would come back as soon as it went through a drive-cycle, every time. Cats are expensive and I needed a smog check, so I figured I'd try the "anti-fouler" trick. That was about 6 months ago; haven't seen the CEL since!:cheers:

Well, dammit. Light came back on. Yay.

I’m going to get an anti fouler. Any tips?

 

[08H3]

My Alpha started to occasionally give me the P0420. Started about once every other month. Progressed to once or twice a month. Eventually, it would come back as soon as it went through a drive-cycle, every time. Cats are expensive and I needed a smog check, so I figured I'd try the "anti-fouler" trick. That was about 6 months ago; haven't seen the CEL since!:cheers:

So you went through inspection with the anti-fouler and they didn't catch it? I'm not in CA, so I don't have firsthand experience, but I've heard stories that they will fail you for almost anything.

 

[fowlken8]

how do you know which O2 sensor to install the non-fouler on?

 

[alrock]

Downstream. It pulls the O2 sensor from the exhaust stream so it will give a cleaner reading than one in the typical position.

 

[650Hawk]

So you went through inspection with the anti-fouler and they didn't catch it? I'm not in CA, so I don't have firsthand experience, but I've heard stories that they will fail you for almost anything.

They really don't do much of an intensive inspection anymore in CA. They don't even put your vehicle on a treadmill, like they used to. Now it's simply a matter of plugging in to the computer, and letting the computer communicate with the vehicle for about 10 minutes.