it seems these things have wideband 02s up front. Voltages for them look fine but voltage moves very little (3-9V-4.0V generally) so not much oscillation to compare to the post cat sensors. However, I'm only getting P0430 so it's related to the front cylinder bank cat. However, looking at some quick logs I don't see much variance between B1 and B2 Sensor2, at least to the point where I feel I'd get only a P0430 and not a P0420. I'm not one to throw the parts cannon at a vehicle and this is no different. Unfortunately my data logger for my other cars doesn't have a PID for the front o2s so I used torque to monitor those so they won't show in the image below but just know that the front o2s aren't moving much off of lambda 1 (14.7 AFR/4.0V) 17.25%TPS is actually idle on this thing.

What is holding me up:


1. I cannot see much fluctuation in the front o2 to compare to the rear to see if the waveform is in fact following and thus indicating the cat isn't doing it's job well
2. Bank 1/2 sensor 2 are close enough IMO that if one was throwing a code i'd think the other would also.

Any input would be appreciated. I know I can use a spark plug anti-fouler to get the sensor out of the airstream to likely bypass the code. I also may be able to use a resistor to set a .800ish V output to the PCM to make it happy to pass emissions but I'd rather not do those things.

Thanks much,

Dave

 

I had the same error- cleaned both 02 sensors, cleaned the MAF and throttle body, reset the ECU haven't seen codes return in many months

 

How exactly did you clean the o2s? And which did you clean? If it was the upstream you would have gotten different codes than p0430. And if it was a dirty MAF it would also give different codes but also affect both banks, ditto throttle body.

Dave

 

I'll have to look it up but I think the P0430 is a Cat code and not related to the O2 sensors.

Someone correct me if I'm wrong please

My car throws a Cat code once a year.

I clear the code and it takes many months or a year to come back.

 

Your A/F sensors at around 4.0V are reporting a very lean condition, as if there were a vacuum leak in the system. I.e., it may be worthwhile to research that issue to get the engine running in a normal A/F sensor range before firing the parts cannon...

Ericthecarguy has a video (of course!):

 

Remove upper and lower, I did not need to unplug the connector just twist them, spray liberally with carb cleaner, wipe them off with clean rag, re-install. Yes MAF is not directly associated and does not cuase your erroro code but all I previously mentioned do directly greatly influence the MPG and by doing all of them mine MPG went up @20% and I've never seen my error code again. No cost in doing any of these and they are all "quick fixes" little time invovled. Can't hurt. Be sure to reset your ECM after doing these.

 

Thanks for the input. I was trying to find an actual voltage correlation to AFR for this sensor but found nothing. I do know I am not lean and i'll explain that as we go here. I've seen this video years ago and his issue is an o2 heater circuit issue which is not my issue. I do love ETCGs videos and I do watch his southmain auto youtube channel and appreciate his above average diagnostic abilities. With that said, I have checked fuel trims and they're well w/in the fueling parameters on both banks (+5 to +6 for LTFTs). I suspect my scanner is not interpreting the WBo2 PID properly and you can sort of validate that by looking at lambda. It's reading .99-1.00 lambda but the AF sensors are showing ~4.0V. There are codes that would be thrown for lean on either bank if this was the case (P0171 or P0174) and fuel trims would be maxed at +25 as it's added as much fuel as it can and it's still not stoich or close to it. Even if was running lean the logic of the P0420/P0430 is to use waveform data comparison between front/rear o2. This is a very broad example and the numbers are not accurate but if the front o2 wave form is say at 30 Hz and amplitude is .800V (For a narrow band) the rear should NOT be following the frequency and/or the amplitude. Here is a basic illustration.