Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

P0430 code after filling up.. cats have less than 6k miles.. help

Recommended Posts

I just bought a 02 996 cabriolet. It had been sitting for awhile due to engine rebuild. Test drove for at least 70 miles no code. Ran fine. Scanned it before buying.. no codes, no pending codes, no deleted codes. 

Driving home the gas tank got to just under 1/4 tank and it started surgining/ bucking. Stopped filled up with 93. Better but still surging. Then the light came on. Stopped and put Techron in and reset light. Drive fine for almost 200 miles.. no light.  Filled up again... light came back on shortly after P0430 

cats and sensors were replaced 2 years ago. Less than 6 k miles since 

I do get some  blue smoke on cold start up. Not a lot. Goes away when warm. Also get squealing noise in cold start. Goes away pretty quick. Sometimes I can hear squealing when warm but very faint 

I hooked my scanner up. Pre o2 sensors bouncing around pretty good and post pretty steady at .7



Any ideas? Fowler plug from old gas? AOS?  Or could it really be the cats even though pretty new 

Edited by Cavy
Link to comment
Share on other sites

P0430 (or 0420) takes a while to be tripped (a couple of days of driving with mixed load) because there are a series of tests under different driving conditions need to be run first.


Can you check what are the O2 sensor readings at moderate load and constant speed on a flat road? It may be difficult to tell visually since the post O2 will swing as well but should they should swing less than the precat O2 sensors.


Squealing could be a failing AOS. You may want to check your crankcase vacuum with a manometer (should he around 5 inches odlf water vacuum).

Link to comment
Share on other sites

It was difficult to really see while driving but at constant speed with consistent gas the post cat  seemed to stay pretty steady unless I let up on the gas. Depending on how much gas I was giving or not it was bouncing all around. 🤷‍♂️

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.