P0430 advice - Durametric data attached

[Tett]

Hi, folks. 2002 Boxster S here. I'm wondering if anyone would be willing to look at the attached Durametric images of my O2 sensor voltages and advise me on whether it indicates replacement of any particular sensor is in order.

I am throwing a periodic P0430 code, a bank 2 CAT efficiency code. To be thorough, I swapped my sensors left and right. The code returned as P0420, a bank 1 CAT efficiency code. Since it followed the sensor, I know a sensor is the place to start, and I figure it's the one after the CAT. Anyone know any different? What would you do? I'm attaching Durametric graphs. They don't look that different to me (from one side to the other). I expected a difference. Any opinions are appreciated. At this point, I'm planning to replace the Bank 1 post CAT sensor. Bank 1 is the first picture, Bank 2 is the second. Thanks,
Jim

[oldskool73]

I'm no pro, so wait for someone more knowledgeable to chime in before you do anything, but I do know the pre-cat should be going up and down regularly and the post-cat should be a flat line. Bit more info in the opening paragraphs here... https://sites.google.com/site/mikefocke2/oxygensensors

[Jamesp]

If your after cat sensors are bouncing, you need a new cat. Contact forum member Itsnotanova (Woody) and you'll get away cheap.

[Tett]

Not sure I understand why it wouldn't be the sensor since the code switched from one side to the other when I switched the sensor?

Originally Posted by Jamesp

If your after cat sensors are bouncing, you need a new cat. Contact forum member Itsnotanova (Wally) and you'll get away cheap.

[steved0x]

When the o2 sensors get old, they don't react/respond as quickly and if your cat is nearing end of life, you can get those codes. Theory: It might even be caused by the o2 sensor ahead of the cat, if it I not responding as quickly and letting bits of (very slightly) too rich/too lean mixture, which exceeds the limits of the ecu for post cat readings.

My cats were like this at around 120,000 miles and I used to get the occasional code like this, and after replacing some sensors due to aging codes and I think a heater code, those cat efficiency codes stopped

You might have a little bit of life left in those cats

[911monty]

Correct me if I'm wrong but the parameter you have selected in your graphs is the PRE cat sensors, is this correct? If so then they should be swinging up and down between rich and lean. The graph you have indicates very aged PRE cat 02 sensors and both should be replaced. How many miles are on this 02?

[911monty]

This is my pre cat 02 sensors at about 88k, they are starting to get sluggish but this will give you an idea of what they should be doing.

[Gelbster]

Carefully research the Bosch Interchange number from the correct Porsche part number for your specific year "S". Change out all four with Bosch. Pelican has the correct parts

[Tett]

I have pre and post on the same graph. One pic is bank 1, one is bank 2.
153000 on the car.

Originally Posted by 911monty

Correct me if I'm wrong but the parameter you have selected in your graphs is the PRE cat sensors, is this correct? If so then they should be swinging up and down between rich and lean. The graph you have indicates very aged PRE cat 02 sensors and both should be replaced. How many miles are on this 02?

[911monty]

At 153k it's time...... I'd change all 4 as Gelbster has said. But you should change at least both pre cat 02s. Some say only change the bad one, but you're there "Git er done".

[steved0x]

I just replaced my cats with some takeoffs from a car that had only 10-20K miles. My takeoffs with 129,761 miles are available, I didn't get any Cat efficiency codes after changing a few O2 sensors but they are definitely nearing end of life. You could probably find a used set from Woody with much less miles for a good price.

[Tett]

Thanks for all the help, folks. I'll start with the sensors and then hit up Woody if that doesn't solve the issue. Thanks.