P0430? What to do?
 

Hello, I scanned a p0430 code on my 01 Boxster. I'm wondering what steps I should take to find the problem. Should I start by clearing the code with my scanner? I'm a newbie with scanner tools. If I clear the code and it's still an issue will the CEL come back on? After that, what should I check? Thanks for your help.

P0430 indicates that the main three way catalytic converter on bank 2 conversion level is too low. Clear the code, if it returns, you need a new cat.

It can also be a bad O2 sensor, the post cat one. Even if it isn't the O2 sensor you may be able to keep it going and pass inspection for a while by changing your driving style. Don't tool around at low revs, but let the engine sing and drive in a lively style. I have a dying cat that I have kept going for 2 years now by doing this. I do have a replacement manifold/cat sitting on a shelf, ready to go in if the light comes on hard or I need to pass inspection.

BB, don’t jump too fast at changing the o2 sensors. I had p043 codes as well and I instantly jumped to changing all four o2 sensors, which didn’t solve the problem. It took about 1 1/2 years of messing with 2- AOS, oil filler tube, and various vacuum leaks on the intake manifold. I would clear it and it would go away for about 200-300 miles but would come back with p0430, p1130, p1128, p1133 codes. I finally found cracks on the oil filler cap Oring that probably contributed to the codes and also cracks on the gas cap. Since replacing both caps I’ve not had a code in six months and 5k miles. Not saying it was only the oil and fuel caps, but rather start looking at the small stuff first before jumping to the o2 sensors and the cats. My 2 cents.

Black_Boxster did you ever resolve this issue? What were your findings?

I am in similar situation, Occasionally popping CEL for a P0430. Hoping it is not the cat. Planning to check o2 voltage with code reader to compare pre and post cat 02 voltage on both banks.

I may just need to give it a good spirited drive or two, too much commuting.

Exhaust leaks at or before the post cat O2 sensor can also cause the P0430 code.
Pin holes at the O2 sensor bung weld can cause the code, and can be very hard to detect.
Cats are actually designed to last the lifetime of the car. So if you have had no other problems with the car that could affect Cat health, you always use good fuel, your fuel trims are not constantly rich or lean. Your AOS is not or has never been faulty. Then I would look for other causes for the code.
Anything that could cause excess oxygen into the exhaust or a fault with the O2 sensor its self.

What year is the car and how many miles??

It is a 2001 S with 125k, AOS replaced at 58k. Possibly it is failing again and fouled the cat. Not sure that would only affect one bank and not the other. Checked o2 voltage and bank 2 sensors are chasing each other, post cat voltage is wave between .15-.75v.
Bank one looks ok, post cat voltage pretty flat at about .68-.72v.

This P0430 code can be very difficult to diagnose properly.
It could be the cat as JFP stated, but they are an expensive part to just replace without knowing for sure that it is the problem.

A few things that can cause the code other then a bad cat are.
Exhaust leaks
Leaking fuel injectors
Vacuum leaks
Bad O2 sensor

You most likely don't have a vacuum leak issue because your Bank one O2 sensors seem ok. A vacuum leak would affect both banks.

So I would look very closely at the exhaust system on bank 2 for any leaks.
It just takes a pinhole size leak to cause this code so they can be very hard to find.
Check the exhaust clamps as well.

You could swap the post O2 sensors from side to side and see if the code follows the sensor or stays on bank 2. That is a way to prove the sensor good or bad.

You can use a infrared temp gun and check the temp of the cat to see if it comes up to operating temp to function properly.
This last test is a little tricky to do correctly.
Lots of Youtube examples but you have to watch the right ones to get correct info.

I will see if I can find one or two correct ones to watch and post a link for you later today.

When you check the exhaust also look at the condition of the cat, any dents or things of that nature. Strike it a few times with a rubber hammer to see if anything is loose inside.

Any damage like that kills them.

Have you had any other codes or any other issues currently or in the recent past?
Does it seem to run correctly and strong?
Start easily?

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.

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.

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.

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 :cheers:.

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.

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

Sine wave

http://986forum.com/forums/uploads02...1605665919.jpg

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.

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???

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

Sent from my SM-G970U using Tapatalk

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

Why? Wouldn't recycling/reusing an item that reduces CO output be a good "eco" thing?