Pending P0420 on road trip

Well, I finally got sick enough of Sacramento to leave. Yesterday I made it to Winnemucca NV, and tonight I stopped in Rexburg, ID.

I always use 91 octane in my truck. I noticed yesterday in Nevada that the gas contains "up to" 10% ethanol. Is it possible the gas is causing this pending code to appear, and reappear? To my knowledge, this is a first for my truck, so the timing is suspicious. No noticeable change in driving or power.

I cleared it three times and it comes back, but only after a few hours of driving. It has not yet popped an actual CEL, I just periodically run scans on the scan gauge to see what's what.

Final destination is North Dakota. I haven't yet checked to see what their emission laws are, but if this is an actual issue and not just a temporary side effect of the fuel I have access to, I would be curious to hear suggestions to remediate.

Thanks all

 

Typically with old cats I find poor fuel quality is the last straw to break them, my own trucks have had this happen.

It won't get better, it will trigger after about 10 min warm up and 10 min of highway driving, but it really varies with requirements.

It doesn't look like ND requires smog testing, so you can leave it until you decide what you want to do.

Read up on cat replacements, most aftermarkets last for a year or 2 then trigger p0420 again.

My personal truck has cat codes and I really don't care, but that's me.

 

Thanks @Bishop84 , I appreciate the info.

 

I might straight pipe the sumbitch and call it a day.

 

Gas in CA also contain up to 10% ethanol as well so that will not change anything

 

Maybe I just never saw the sign in CA. I almost always used the same Shell station in West Sac near work. It caught my eye at the first fillip in Nevada.

 

u have a sc?

 

I do not. I run 91 just cause it gives me good feels, and the specs in the manual are "based on 91 octane"

 

ive been using arco 87 for a decade, keep using it if it makes u feel good

 

Is there a consensus on how long an OEM replacement is likely to last? Honestly I am surprised the 21 year old originals are just beginning to act up. Also surprised they lasted that long without getting cut off by some scumbag.

 

And your point is?

 

Update on the pending code for kicks. Got two separate 2/3 tank fill ups today with 91 and no ethanol specified on the pump. Also ran a bottle of STPs highest grade fuel system treatment before the first fill up. Pending code has not yet returned, although I know it still might. Logged ~460 miles driven today.

Truck has 164,xxx on the clock.

 

Another update - good news. This morning after hitting the road, my monitors switched from not ready to ready, and the pending code did not return once today. It *seems* like I may have gotten away with just some gas my truck wasn't used to drinking. Hit it with another bottle of system cleaner with today's last fill up. They didn't have 91 so I had to get 89 like some peasant.

I'll find this thread again if the code comes back to haunt me in the end. But I gotta say, this truck continues to not give me grief. It's almost comical. A little piece of plastic that surrounds the sun visoir clip point broke on this road trip shortly after I found about the pending code. I joked in my head about posting on TW that it was time to part out this pile if it keeps acting up

This truck owes me absolutely nothing and just keeps going.

 

This is exactly how my bad cat/P0420 saga began. Came on one day after filling up before a long wheeling trip, reset it and it stayed gone for awhile. Eventually came back, reset...gone for awhile. So on and so on, until eventually it just stayed on. New cats fixed the problem. If it was an exhaust leak I imagine it would come back on pretty quick after the emissions monitors reset.

 

Did you go with an after market catalytic?

 

Yeah, 50 state legal Magnaflows. They were a lot cheaper then in 2018 than they are now, but still far cheaper than OEM.

 

I'm one of the lucky ones that got a Cat/O2 simulator before they were taken down off their website because of new EPA laws. 5 minute under-seat install. No emissions testing here.

 

IIRC the manual lists 91 RON. that is a non-US gas rating which equates to 87 octane in the USA. these trucks were made to run 87 here, not 91. putting anything more than 87 in a stock Tacoma is just throwing away money.

 

P0420 CEL is a right of passage when you own a 5VZ

Had it on the Taco and the 4R

Sometimes it's bad gas, a bad o2 sensor (replace with OEM), and lastly a bad CAT

 

And sometimes it's because you've deleted your cat.