P0430, Bad MPGs, Normal Driveability.

[bowtieman55]

My '97 picked up a P0430 code a month or so ago. I didn't think much of it and erased the code. A week ago, the SES light came back on. I pulled the codes this afternoon and it was the same P0430 twice.
In the past week, my fuel mileage has fell off (1/2 tank of gas in 60 miles). The truck still runs fine, as it always has. I replaced all four O2 sensors (Bosch) at 202,741 miles and performed a complete tune-up and fuel filter change at 218,444 miles.
I'm thinking that with 222,*** miles and the original catalytic converters that maybe it's time to replace them with new units?

 

[SunlitComet]

4mpg sound a bit impossible without a major fuel leak. i would not use bosch sensors again. delphi or delco only. if you were to put a new delphi sensor post converter for bank 2 and the code came back then yes replace them both. if you can tho first see someone at at a shop who can read the waveform output of all four sensors at the same time. if the post sensors closely mimic the ones in front then the converters are likely inert. i don't think you scanner can even show at least one.

 

[Jerky Arm Ape]

My '98 throws the same code.
Since you have replaced all of the 02 sensors, I would say that it is indeed time to change the converters.

I took mine to a shop to have it scanned and the mechanic said the code basically means that there is no catalytic converter present in the system.
That if you replace the down stream 02 sensor and the code is still present then you will have to replace the converter itself.

---------- Post added at 11:31 PM ---------- Previous post was at 11:23 PM ----------

Didn't see sunlit's post...
I will agree with the statement about Bosch vs. Delphi.
At one time Bosch made good quality products.
Quality has fallen off a bit, I used to use their ignition parts on my vw engines.
Now they are just an expensive name brand.
Also just because a part is new doesn't mean that it's good.
When I replace a part to fix a problem and it doesn't work (outside of alternators and a such that can be tested) I have to come up with in theory tests to make sure the new part is good itself.
It's quite agrivating.

Is there a way to at home test the 02 sensors?

 

[SunlitComet]

only with a slew of expensive equipment and various gases.

 

[laneo2494]

Hi guys, I'm hoping to get a couple questions answered by reviving this old thread. My father's (and formerly mine) '98 Yukon threw the same P0430 bank 2 code the other day. I pulled the code and started researching the issue here this morning. I understand that there are two catalytic converters - drivers side/bank1 and passenger side/bank 2 - and two sets of O2 sensors - one before and one after the cat on both driver and passenger side. I plan on getting under the truck tomorrow to take a closer look to see if there any obvious issues like a broken wire, etc.

Now the code specified bank 2 so should I start by replacing both the passenger side O2 sensors or can I get away with just replacing one of them? If so, how do I know if it is the 02 sensor before or after the cat?

Given the age and the miles of the truck (approaching 199k) I understand that this could be a much bigger issue but I'd like to start with the simple things first. Any and all info is appreciated.

EDIT: forgot to mention that my father said the truck has been running absolutely fine but he is going to monitor his gas mileage going forward

 

[laneo2494]

Bump.

I managed to crawl under the truck tonight and tried to snap a pic of the passenger side O2 sensor beyond the cat, the attached pic is what I'm working with. Does that weird discoloration ring mean anything in particular?

 

[robstor]

Yeah I had that code last year. Wasn't o2 sensor but the cat went out.

 

[Immortalmort]

I had the O2 sensor code and the cam pos. sensor code a few months ago in the summer, replaced the cam sensor only to have the code keep coming back. A little closer actual observation of the truck showed that the loom of the rear o2 (and maybe transfer case? can't fully recall) had come free and been torn apart by the front drive shaft u-joint connection. Spliced the wires back together, replaced the ENG1 fuse in the fuse block under the hood, cleared the codes and voila! Runs like a top again.

Not sure if related, but worth the ten second look under the truck to check for broken wires!