P0420 and premium fuel

[Andrew1972]

I had to put 87 octane in rural VT in a near empty 2007 Acura MDX with 185k. Within 50 miles the check engine light clicked on with P0420 announced in NAV screen.

It went another tank topped with regular by in-laws who borrowed. Now with 60% premium/40 regular to make 91 octane it clicked back off.

Is this coincidence or related?

 

[CT8]

Here is a link that defines the code.

 

[Warstud]

Probably a "Cylinder Misfire". The wrong octane can throw the timing off. What grade of gas are you suppose to be using?

 

[MoneyJohn]

Can't say for sure. I had this problem with 2006 Sentra. Every time after I filled up the gas, it would come up and used to go away randomly.

A lot of things (O2 sensors mainly) were replaced during the period of 2 years and it was the Vapor Canister Vent Valve/Solenoid. It was this one that I changed with, https://www.rockauto.com/en/moreinfo.php?pk=3789141&cc=1432237&jsn=379 Just keep it in the back of your mind in case it is not related.

 

[anndel]

Could be your catalytic converter is getting clogged and may need replacing. If you can get to it pull it and shine light through one side while looking through the other. If you can't see the light or it's a small circle about the size of a quarter it needs to be replaced.

 

[JTK]

Had you ever gotten the catalyst inefficiency code before in this vehicle? That's about the age/mileage this can crop up. I would say it's a coincidence, but who knows for sure.

 

[StevieC]

Could be just some bad gas, I would see if it comes back.

 

[clinebarger]

This comes up with customers vehicles quite often, Probably one of the most frustrating things to convey to a customer as well.

When the Catalyst on your vehicle was NEW, It had a TON of oxygen storage capacity, You could throw A LOT of raw fuel through it & STILL be very efficient at burning/converting the hydrocarbons.

Now.....200,000 miles later, It may have the absolute Minimum Oxygen Storage Capacity! Any number of incomplete combustion events will now overcome the capacity & set Catalyst Efficiency DTC's.

An Anti-Fouler to space the secondary O2 sensor may get you a couple more years of service out of the Catalyst.

 

[bbhero]

Really good post ^^^^^^

My catalytic converters went bad not too long ago... No surprise really. At 240k miles. These are only warrantied for 80k miles I think... As per Federal guidelines.

 

[slacktide_bitog]

You will probably need a new cat. Eastern makes good cats, and they have a 5-year/50k warranty (the EPA only requires a 2-year-25k warranty for aftermarket cats)

The CEL turns off after a number of cycles without the problem coming back. More than the time you've had it with your most recent premium fill-up. Your car has a knock sensor.

 

[The Critic]

Most likely you are due for a new CAT. There is little to no relation between the P0420 and the premium fuel.

 

[Californiabob]

I used to get these codes on a regular basis. I noticed over the last few years, the California emissions was going
up - hc. I used a variety of cleaners for the gas and the oil.

my guess the injectors were getting clogged. went away permanently after "cleansing" - car had over 200K.

try different types/brands of injector/gas cleaners with each tank.

 

[LeakySeals]

How much oil do you consume on a regular basis?

 

[mightymousetech]

Originally Posted by madRiver
I had to put 87 octane in rural VT in a near empty 2007 Acura MDX with 185k. Within 50 miles the check engine light clicked on with P0420 announced in NAV screen.

It went another tank topped with regular by in-laws who borrowed. Now with 60% premium/40 regular to make 91 octane it clicked back off.

Is this coincidence or related?

Originally Posted by madRiver
I had to put 87 octane in rural VT in a near empty 2007 Acura MDX with 185k. Within 50 miles the check engine light clicked on with P0420 announced in NAV screen.

It went another tank topped with regular by in-laws who borrowed. Now with 60% premium/40 regular to make 91 octane it clicked back off.

Is this coincidence or related?


With a 2007 MDX, it was only a matter of time before the bank 2 cat died. Running regular fuel certainly did not help.

Google "2007 MDX bank 2 cat"

There was a recall to update the engine software, and an extended warranty on the cat.