Seafoam caused CEL??

[Back in a Bowtie]

So I just did a seafoam top end treatment (2nd time) at 30k miles. The first time I did it (at 15k) all went smooth. This time however I got a CEL. So I changed my oil and checked / cleared the code. It was P0420 (cat efficiency). So I figured the code was just from all the carbon flowing through but it came back. Whats the move here? Should i run a fuel treatment? Premium gas and drive it hard for a while? The truck feels like its running great so I'm just a little confused by the whole thing

[O_J_Simpson]

You cleared the light. Did it return?

[Back in a Bowtie]

yes it did return. i had it cleared. drove about 10 miles home and it has sat since. Got in today to go to the gym and the CEL was on

[txab]

Use only top tier fuel and see what happens. Crappy fuel can cause this issue

[TJay74]

Crappy fuel will not cause this issue. That is a post cat O2 sensor code. That means the post cat sensor is showing the catalytic converter is not working. I would take it into the dealer and have them check it out, the cats are covered for 8yr / 80k miles I believe. Usually a failure of the cat is due to a fueling issue like a bad MAF, bad injector that is dumping way to much fuel. Most of the tings that kill cats are from them getting too hot and melting down.

[Brianibew]

If you do a search, somewhere on this site someone else did a crc or seafoam type top end treatment and had the cat code come up shortly thereafter. I believe he had to have the cat replaced.

[txab]

Crappy fuel will not cause this issue. That is a post cat O2 sensor code. That means the post cat sensor is showing the catalytic converter is not working. I would take it into the dealer and have them check it out, the cats are covered for 8yr / 80k miles I believe. Usually a failure of the cat is due to a fueling issue like a bad MAF, bad injector that is dumping way to much fuel. Most of the tings that kill cats are from them getting too hot and melting down.

Poor quality fuel over time can cause an issue with the O2 sensors and cause a post cat code to be thrown, not because of a bad cat but because the comparison that is done between the pre and post cat sensors is out of range. I know this because I've overseen our fleet vehicles.We started having post cat codes being thrown a few months after switching fuel suppliers. Never was there a bad cat. Finally after several O2 sensor changes we narrowed it down to fuel. Switched back to our previous supplier and never had the issue again.

 

With that being said, yes, cats should be checked also

[Ag76]

If you do a search, somewhere on this site someone else did a crc or seafoam type top end treatment and had the cat code come up shortly thereafter. I believe he had to have the cat replaced.

I think the poster in that thread you're referring to used Seafoam. So far, I don't remember anyone using the CRC Intake Cleaner having problems with the cat.

[Back in a Bowtie]

well i cleared the code again so only time will tell now

[HondaHawkGT]

I've used the CRC cleaner a couple times now without issue. It's basically a highly concentrated version of Chevron Techron. Cat safe.

 

I've read in the past that Seafoam can cause problems with the CC's. Seafoam is best left to gunked up carbs, not expensive new trucks.

[07Softail]

Do away with the cats and problem solved!

 

RT

[HondaHawkGT]

Might well do LT headers since you're doing the cats!

[fondupot]

Even when they do the intake cleanings at the dealer, they say an engine light might come on. It's likely a piece of lose carbon that broke off and landed on the O2 sensor. Should go away with time.

[Back in a Bowtie]

cleared code saturday and CEL popped back on today. Still well below 100 miles since the treatment and oil change. Got a decent trip coming up this week so hopefully its gone by then. Switching to kooks and removing the third if a change has to be made.

[Back in a Bowtie]

Even when they do the intake cleanings at the dealer, they say an engine light might come on. It's likely a piece of lose carbon that broke off and landed on the O2 sensor. Should go away with time.

should i / could i just clean the O2 sensor?