New code popped up!

[drperry]

P0420 showed up in my truck today...

What exactly do they mean by:

"Catalyst system efficiency below threshold" ?

Never seen it before... But I pulled out the hypertech tune and went back to stock to see if it's something to do with the 93 octane tune

 

[Bigredmariner]

More here.

OK, so what does a P0420 code mean anyway?

As mentioned above, the code's description is Catalyst System Efficiency Below Threshold (Bank 1). OK, now tell me that again in plain English please.... let's break it down: the catalyst system being referred to is your three-way catalytic converter; so the catalytic converter is not working properly (i.e. it's not efficient). Bank 1 refers to the side of the engine which contains cylinder #1. On inline engines such as 4 & 5 cylinder engines, there is only one bank. So, to really simply things let's just say that the efficiency of the catalytic converter and/or exhaust pipe and/or O2 sensor is not so great.
There are no symptoms so why should I fix it?

Great question! A P0420 code will cause no symptoms aside from the MIL (malfunction indicator light) will illuminate. The reality is there is still something wrong and your car needs attention in order to be in excellent running condition. A poorly maintained car will run less efficiently, burn more gas, and cost you more money in the long run. Plus, if your check engine light is on for a P0420 code and you decide not to fix it, another more serious code could be triggered and you'd never know. The MIL lights up whether you have one code or ten! While I have your attention, don't forget to do oil changes as the owner's manual schedules and keep those tires inflated to the proper PSI.

 

[drperry]

So my brand new cat is already on its way out? Giggity.

Thanks J-Rod

 

[Bigredmariner]

Brand new? How about O2 sensors? New too.

 

[drperry]

I'm thinking it's more likely the after cat O2 sensor... I usually get a P0137 after awhile with the 87 octane Hypertech tune in the thing... I guess the premium tune is worse for it

 

[sand man]

it simply says...remove the cats cuse they dont work

 

[Draenor]

I'm thinking it's more likely the after cat O2 sensor... I usually get a P0137 after awhile with the 87 octane Hypertech tune in the thing... I guess the premium tune is worse for it

The O2 is probably on its way out. Your on the right track.

 

[DV2000NJ]

It could also be a pre-cat exhaust leak. I had a P0430 (same thing, bank 2) on my truck, and I thought it was a bad O2, but when I pulled the y-pipe off, the exhaust shop had missed a little spot on top when they welded the cats in.

My Mom's Subaru also has the P0420, and she's got an audible exhaust leak, that sounds far enough forward to be before the cats.

The easiest thing to do, is switch the post-cat O2s, and see if the code goes away, follows the O2, or stays on the same side.

Also, this is a great site for looking up trouble codes.

 

[Stumpuller6.5]

It could also be a pre-cat exhaust leak. I had a P0430 (same thing, bank 2) on my truck, and I thought it was a bad O2, but when I pulled the y-pipe off, the exhaust shop had missed a little spot on top when they welded the cats in.

My Mom's Subaru also has the P0420, and she's got an audible exhaust leak, that sounds far enough forward to be before the cats.

The easiest thing to do, is switch the post-cat O2s, and see if the code goes away, follows the O2, or stays on the same side.

Also, this is a great site for looking up trouble codes.

I`d put money on an exhaust leak.

 

[drperry]

I don't have a pre-cat
After it piled up and took out my main cat, I only replaced the main cat.

The after cat O2 sensor should be the same one as the front pre-cat sensors, right?

It could be an exhaust leak, I suppose... Though, a faulty O2 sensor is still a possibility... Or both

Generally the P0137 only kicked in under load... Like going up a hill, foot to the floor in 5th gear


And Faisal, removing the cats is a federal offense for us