SES w/code 0430

Let's see: DTC P0420 = Three way catalyst system low efficiency. DTC P0430 = EVAP system no flow during purge.

Don't see any relationship between those two DTCs and the pre-cat O2 sensors. Were you just shotgunning?

Looks like he gave er' both barrels!

Doc

No...DTC P0420 is 'catalyst system efficiency below threshold (Bank 1)' and DTC P0430 is 'catalyst system efficiency below threshold (Bank 2)'.

- Jon

looks to me like he was shooting the messenger (O2 sensors) of bad news (catalytic converter)

Correct.

(Bank 2)'.

Doesn't apply on a single outlet cat. In this case, a P0430 is a manufacturer defined code.

This truck does have 2 cats on it....remember..??

- Jon

Quote:

"I changed out the pre-catalytic converter sensors (it has two-into-one exhaust) but I still have the problem."

In any mechanics mind, this statement means you have an exhaust Y-pipe and one catalytic convertor. Perhaps an accurrate description of your truck in the future will enable us to help you better.

Anyhow, P0420 and P0430 have little to do with the pre-cat sensors, so why you changed them is beyond me. If you passed emissions with flying colors (especially hydrocarbons) that only means one thing, the post-catalytic sensors are shot. You probably fouled the hell out of them when you blew an ignition component and tried to start it for two hours.

Doc

I'm not sure what it is I should remember, but you are correct, I checked the wiring diagram and there are 2 pre-cat O2 sensors and

Sorry, Doc...I'm not a mechanic by trade (does it show??). My attempt at diagnosing problems probably has to get a bit better, eh? Thanks for the information though. I'll see if I can put it to good use.

- Jon

Mitchell was wrong? Gee... first time I've run into that. Makes me remember a Lumina with the 3.4DOHC that came into the shop several years back with a broken timing belt. Granted its a poor arangement but Mitchell's help only made things worse. Bob

My SES light would come on, I would read P0430 code, reset the system, and a couple of days later it would come on again. I finally got tired of playing with it and just changed the post cat O2 sensor on the right bank. It hasn't turned the light on again in the last month or so. I also checked the sensor voltage (OBDII and laptop)while the engine was operating going down the highway and it stayed a "0" (zero) for both the short and long term. After I changed it, the voltage started changing along with the other one on the left bank.

You need to find a wife or a girlfriend (both?) who is literate and can read your lappy for you going down the highway, as well as tell you what your laptop says....

~KJ/TLGM

Where is the fun in that? besides I would have better uses for a fluffy, than have her doing that.

"reading your lappy" was in inference to road head.... hence the "and read your laptop for you"

~KJ/TLGM