P0430? What to do?

[JFP in PA]

What he should be doing is comparing the O2 sensor voltages before and after the cat, if the voltage traces are following each other, the cat is toast.

[blue62]

Staircasesurfer

Here are two youtube video's to watch

https://youtu.be/RAC0E6apXq0
https://youtu.be/vyVnhCIMDnw

One shows how an exhaust leak can be the cause of the code.
Also a proper diagnostic procedure to correct the issue.

The other video shows that it was a Cat issue also using a proper diagnostic procedure.

Look closely at the O2 signal graphs in both video's.

The video by ScannerDanner shows the pre and post cat O2 sensors paralleling each other in frequency and amplitude. This is what JFP is referring to in his post.
But the test has to be done under the proper conditions as ScannerDanner has done.

The other video shows the post cat O2 sensor signal rising and falling with the pre cat O2 signal but not with the same frequency and amplitude. The signal is more biased to the lean side.
This is a signal you could also get if the cat was not hot enough.
Here again the test has to be done under the proper conditions for the test to be meaningful.

Hope they give you some insight into fixing your PO430 issue.

[staircasesurfer]

Originally Posted by blue62

Staircasesurfer

Hope they give you some insight into fixing your PO430 issue.

Blue62,

Thank you for the information, this is super helpful. I will take a look at exhaust for leaks, check the cat to ensure it has not separated, swap O2 post cat from bank 1 to bank 2 and run these tests this weekend. I guess if worse comes to worst I can hopefully source a low mileage used header online. CA smog BAR is such trash.

I will make a weekend of it as I currently am in the middle of window regulator replacements, a cut and buff on the paint, interior carpet dye for the rear storage box and maybe opening up the dash to fix the lovely HVAC foam flaps.

Battery died from not driving enough, upon replacement I can't get the catalytic monitoring efficiency readiness to clear. Have not got the CEL since, took a screenshot of the CEL back when I was commuting 70 miles a day.

Was planning on selling the car a few months ago as my Covid work commute is now about 20 feet. Bed, desk, fridge, desk, shi*ter, desk, fridge, bed, routine.

Last weekend I did plugs & tubes (thank you 986 forum for the boat transom plug recommendation), oil and filters. Took it up local hwy 33 with my girl and we both agreed it's not going anywhere. Always helps to have the lady agree .

I have owned the car for 3 years and everyone said don't buy a used Porsche its a money pit and it will live in the shop. Not my experience at all. Between all the knowledge on this forum and a pretty basic set of tools it has not needed to go to the shop once. One of the most reliable cars I have ever owned, (and that list includes a 90's Toyota Pickup). Bar none the most fun, although my 1972 Skylark was pretty fun as a first car. Can't replace the bench front seat memories from back in high school .

I will keep the post updated with my findings as it may help others track down the P0430 issue.

[staircasesurfer]

Originally Posted by JFP in PA

What he should be doing is comparing the O2 sensor voltages before and after the cat, if the voltage traces are following each other, the cat is toast.

This is what I was checking on each bank, I reread my post and I wasn't very clear, sorry for the confusion. I am getting tracing on bank 2, Pre & post 02 voltage. Bank 1 looks fine.

[JFP in PA]

Originally Posted by staircasesurfer

This is what I was checking on each bank, I reread my post and I wasn't very clear, sorry for the confusion. I am getting tracing on bank 2, Pre & post 02 voltage. Bank 1 looks fine.

Are they both moving the same (straight line or sine wave like cycle)?

[staircasesurfer]

Originally Posted by JFP in PA

Are they both moving the same (straight line or sine wave like cycle)?

Sine wave

[blue62]

Originally Posted by staircasesurfer

Sine wave

Yes that does look like a bad "Cat" waveform.
The green trace shows no bias to the rich or lean side.
The post O2 sensor is moving over the normal range so the sensor is good.
It does not bias to the lean side so no exhaust leak.
Looks like a new "Cat" is needed.

[staircasesurfer]

Originally Posted by blue62

Yes that does look like a bad "Cat" waveform.
The green trace shows no bias to the rich or lean side.
The post O2 sensor is moving over the normal range so the sensor is good.
It does not bias to the lean side so no exhaust leak.

Damn, I was hoping this was not the case with OEM converters being $$$, CA is kind of a PITA with non-OEM "modifications" to smog equipment. I am not sure if I can get a set legally from a junkyard/dismantler around here with all of our regulations. Probably will need to buy off Ebay or get lucky and find one from a forum user. My understanding is that S 3.2L and non-S 2.7L have different sizes.

[blue62]

Originally Posted by staircasesurfer

Damn, I was hoping this was not the case with OEM converters being $$$, CA is kind of a PITA with non-OEM "modifications" to smog equipment. I am not sure if I can get a set legally from a junkyard/dismantler around here with all of our regulations. Probably will need to buy off Ebay or get lucky and find one from a forum user. My understanding is that S 3.2L and non-S 2.7L have different sizes.

Yes it sucks that they are so costly.
I am not sure if the 3.2L VS 2.7L require different sizes.
What was the engine RPM when you took the screen shot of the above O2 sensor readings???

[maytag]

Originally Posted by staircasesurfer

Damn, I was hoping this was not the case with OEM converters being $$$, CA is kind of a PITA with non-OEM "modifications" to smog equipment. I am not sure if I can get a set legally from a junkyard/dismantler around here with all of our regulations. Probably will need to buy off Ebay or get lucky and find one from a forum user. My understanding is that S 3.2L and non-S 2.7L have different sizes.

I have a set from an '04 S with 85k miles.
Message me if you're interested.

Sent from my SM-G970U using Tapatalk

[Gilles]

Originally Posted by staircasesurfer

I am not sure if I can get a set legally from a junkyard/dismantler around here with all of our regulations.

Staircasesurfer, I don't believe that you would be able to buy a cat (legally) from a wrecking yard in CA... :-(
.