Po420 & po430

[justanother1]

I have been getting codes PO420 & PO0430 in my 97 ex, but this only happens when I run o/d. I'm not sure that the codes and o/d are connected but what are your thoughts? Is there something that I should look for? This ex has almost 150,000 miles on it. There does not seem to be any issues in how it runs or preforms.

 

[aleej]

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

P0430 Catalyst System Efficiency Below Threshold (Bank 2)

when you say when you run o/d does that mean when youre driving with o/d on or off? and just incase you're still unclear these mean that your cat is basically bad.. now bank 1 and 2 in tht=is case im not too sure about mabe front and back i dunno.. this also may be triggered by something else i dunno do some research on 1st what these mean and then research how the syslem works and see if anything pops out at you.. is the truck diriving/idling funny, is there anyother problems (no matter how small) that you can think of...

 

[justanother1]

When i said run o/d, I met driving with o/d on. Truck does not seem to have any idle / driving issues. Idles smooth at 500rpm. It just seems funny that the check engine light is triggered by these codes only when driving with o/d on. I do not know if it is coincidence or if something else is going on but has not showed up yet.

I bought this from my sister and have not done anything except change oil, flush the cooling system, and refill with new coolant. I did get code (don't remember what it was) about 2 months ago that said something about leaded fuel but everything gas station sells unleaded. Been buying my gas from BJ's wholesale club.

We just went away for the weekend and put 280 miles on it without any issues except the check engine light coming on giving me these codes. Have not figured out gas mileage yet, but used 1/2 tank for this complete trip.

 

[aleej]

half a tank for 280 miles.. something dont sound right about that.. how many gallons is your tank, cuz 1/2 tank at 280 miles with the standard 17 gal tank is 32 miles/gal .. but anyway.. so the cel goes off if you shut off the o/d like if you play with the button the light will go on and off?? thats really strange if thatas the case (every time you shut it off the light goes out and everytime you put it back on the light comes on again ) then i havent go t the faintest idea and u may wanna take it to a shop and have it checked out.. if nothing more that to find the problem then go home and fix it your self

 

[justanother1]

aleej, I think that you are reading more into what I'm saying and not understanding what I'm saying. I greatly appreciate your help.

280 miles on 1/2 (standard 4 door 21 gallon) tank. All highway miles. CEL came on after we had the first half of the trip finished.

I can run 600 miles (with o/b off) and no cel. Take a trip (with o/d on) and the cel will come on. Pull the codes and get PO420 & PO430. The cel does not come on and go off when o/d is turned on and off.

 

[Turdle]

Hmmm,
This might seem like a lot of work-
but if you were to swap the rear o2 sensors for the fronts, and fronts to rear-
it would eliminate something-

if the code returns you may have clogged catalytic converters
if it changes to a "rich -lean" condition report, it would indicate bad o2 sensors.

It's free, and worth a shot.

You don't happen to have an exhaust leak? Could you check the DPFE hoses real quick?

 

[aleej]

aleej, I think that you are reading more into what I'm saying and not understanding what I'm saying. I greatly appreciate your help.

280 miles on 1/2 (standard 4 door 21 gallon) tank. All highway miles. CEL came on after we had the first half of the trip finished.

I can run 600 miles (with o/b off) and no cel. Take a trip (with o/d on) and the cel will come on. Pull the codes and get PO420 & PO430. The cel does not come on and go off when o/d is turned on and off.

ok sorry i have a 2door so that seemed like a lotta miles to me.. and yes i was misunderstanding sry, but i get what you're saying now.. i really havent got a clue then, but id try the 02 swap thing cuz its free and cant hurt!!

 

[Countryboy276]

Hello,
I am receiving both PO420 & PO430 codes was going to replace the catalytic converters. Would I benefit from installing performance catalytic converters? Is there that much difference between the stock and performance?

Thanks
David