Hello CL! I've posted a thread a few weeks back on my CEL turning on & off. I've got it scanned and the code that came up was PO430, Catalyst System, Efficiency Below Threshold Bank 2. I already found out where that is located (passenger side) and what I can do to possibly fix the problem. O2 sesnors, exhaust gaskets, check catalysts, etc. But here's what's been on my mind recently about this whole ordeal. I usually use 93+ gas at my local Sunoco which is "super" premium. I've always used nothing but that since I bought the car. But the other day, idk what it was, but something told me to use 91+ gas. Which is still premium just not "super" premium like the 93+ I usually use. Anyhow, before I got that gas, my CEL was on like usual. It has tendencies to go on & off. Randomly. After I pumped the 91+ gas the CEL turned off immediately. This was about 2 weeks ago. The 2 weeks thats passed, the CEL has been unusually off more then before. Then it turned on again yesterday, so I pumped it with 91+ after I got out of work and the crazy CEL turned off again. Can someone give me some type of opinion, advice, anything, on what this can be. Is high octane gasoline bad for my engine? I never thought using the best gas would cause some type of little problem with my o2 sensors. Maybe, I really do not know what to believe. I was planning on getting all 4 o2 sesnors new. But if the CEL is turning on and off simply due to higher octane then what my car requires, maybe I should hold off on the o2 sensors?? Idk. Please, help!

Has anybody ran across a problem like this or similar? Please, ANY suggestions are deeply appreciated. Thanks for your time!

 

Wassup guys? Nobody has stumbled across this problem? I tried searching for some type of thread to help me out. I typed in high octane CEL, o2 sensor high octane CEL, but got nothing. Can I just get some opinions or suggestions about this little issue? Thanks! Anybody who replies, I deeply appreciate your time!


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gas won't change that. Especially not going from 93 to 91, which even then is overkill (the car will run fine on 89). The CEL may go off, btu the code is still there. Chances are your o2's are shot, and your cats are on their way out.

 

This is true^^^ I always run 91 here at 6000ft and 93 at sea level (just for the sake of having a high(er) compression and the timing is set for higher octane fuels from the factory). You will only benefit from getting new O2 sensors, so I'd do that for the sake of good health. If it keeps popping that code, just change the cat and call it done.

 

still not enough to make a noticeable difference. These cars have a very advanced powertrain control system. Most cars can compensate for 2-4 octane points, and that's without Variable Valve Timing. Add VVTi to the very complex self-learning ECU, and your car can adjust it's timing and fuel curves quite a bit. Would I run 87 in it? no. But I would not hesitate to run 89 octane to save the money (around here 91 and 93 tend to be 15-25 cents more per gallon). And definitely don't run octane booster, that stuff is garbage.

I run 89 octane in my ES and every 5 tanks or so I'll send a bottle of Lucas fuel system cleaner/lubricant through. Helps to quiet down the injection tick and I notice a bit of a gas mileage boost. This is especially useful when it goes from 80° one day to 40° the next as it's done so many times here in New England, where you're prone to getting water and eventually when it gets really cold, ice, in the fuel lines/tank. Yes, the Lucas fuel system cleaner also works like drygas to get rid of the water.

 

Replace your post cat O2 sensors. They are intermitantly failing, that's why the light comes and goes.

 

Thanks EVERYBODY! I was thinking on replacing all 4 o2 sensors deep down inside anyway. I can get all 4 brand new NGK brand off eBay for around $340 all together. Once I do, I will post links up after receiving items and successfully installing them. I don't wanna give you guys any links if I can't vouch for them, you know? But anyhow thanks guys! I deeply appreciate all the opinions, suggestions, advice, etc.


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did u try typing the CEL code into a advanced search.....? many threads with that code. there are other things it can be, besides the O2 sensors

 

I had the same problem too, I found an exhaust leak around the 02 sensor BANK2 SENSOR 2 it rusted trough..

 

Oxygensensor.com has OEM Densos for $300 shipped for a 430.

 

man don't replace all 4 right now. Just replace the one that is going bad. Very easy to do. pick yourself up an O2 socket and it will be so easy your sister could do it

 

^+1 Do post cat sensors first. Those cause the most issues. My new pre cat sensors are still in boxes. Don't know when I'll ever need them.

 

i had that code it was the my o2 sensor but you should only need one i wouldn't go replacing them all but don't use a cheap universal o2 i have had nothing but bad luck with them use the bosh or denso since i used a good o2 i havent had any issues and ill put 89 in every once in awhile it doesnt set any codes off honestly i cant tell a whole lot of differance between the two but i am supercharged which really i should always use the higher octane but at the price of gas lol

 

This is the epitome of pennywise and dollar foolish.

ANY forced induction vehicle should run on minimum 91 octane. With the boost adding to the compression, detonation is infinitely more likely, and one of those times you'll forget when you step on the happy pedal and boom goes the 1uz.

Lower octane gas won't set off a code until it starts misfiring. A stock 400 can very easily run on 89 octane all day long. 87 will knock. A supercharged 400 I wouldn't even think about using anything less than 91.

 

Oh man. I'm glad I see all these posts. Different opinions, different suggestions, different point if views, etc. I would only buy the o2 sensor I need but its kind of too late.. I bought all 4 NGK o2 sensors off eBay brand new. 1 question, why does everybody refer me to Denso or Bosch o2 sensors? What's wrong with NGKs? last time I checked, I thought NGK was a great Japanese brand. Are they no good in o2 sensors? Please, lemme know. Again, thanks to everyone for all the posts and support! I deeply appreciate your thoughts.


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