I've recently started getting The check engine light coming on from time to time. Sometimes it takes a month to come back on after reset/clear, sometimes it comes back on a few days (100 miles or so) after a reset/clear. The code I am getting is P0430 (Catalyst efficiency below threshold bank 2) and once, I got the same P0430, plus P0420 (cat efficiency below threshold bank 1) and P0133 (O2S Ckt slow respnse 1/1), all at the same time.

Any suggestions on what might be going on? The truck seems to be running fine,....and I am getting my usual 12 mpg.......well, actually,....11.7)

I've been running regular/low octane fuel for a few months as a test,....wondering if that might impact Catalyst efficiency somehow (but have never seen that addressed in any tech articles)

This is my last tank of regular octane (for a while any way) will be switching to High octane for the next few tanks to see if I have any noticeable change in performance and/or fuel economy.

Brian in Austin

 

I've run 87 for several tanks with no issues except a possible loss in MPG. I'm running 93 again to check the mileage question.

Before I started running 87 oct, I had a upstream o2 sensor fail and just got an o2 sensor code.

 

JE Robison wrote an article on this in his blog. I would start their.

JE Robison Service — the blog: Those dreaded P0420/P0430 catalyst efficiency codes and what to do

It discusses your situation in detail

 

Did you end up having your catalytic converter replaced?

I have an LR3-2007 V8 with 101Kmiles. I just start seeing this same issue and P0420 service code. I would like to know if it was just your O2 Sensor failing? Or was it the Catalytic Converter?

Thanks in advance,
Mai-ILLINOIS

 

Not yet, my state inspection is good through end of November. I'll reset my codes, drive it for a few days, then see if it will pass inspection.

About 300 miles now since the last reset,....has not come back on yet.

 

Bcolins, since this is an old non updated thread what were the results of your using high octane gas instead of the cheap stuff?

Could you tell the difference when the ECU adjusted your timing?

 

I changed back and forth, and I didn't ever notice any significant change in performance and I never heard any pinging. Seemed like maybe the fuel mileage suffered a bit, but never drove it enough with reg then premium, and tracking the two. I bought a more economical car for my daily driver about 3-4 months ago,....so, its been a while since I have paid attention to it.

 

I had my rear O2 sensor changed out - perhaps this was not really needed. There was no issue with the catalytic converter per the LR technician. I have not seen the code since.