aspiringporsche

I've been in the process of playing "whack-a-mole" with some errors codes on my 2002 996TT and looking for guidance on the next steps without unloading the parts canon on the car...

P0442- Since getting the car, I've had this code pop up on/off and have had consistent issues with filling the gas tank. I've replaced the vent valve as suggested. This at least allows me to fill the tank about halfway before filling gets complicated (i.e. pump constantly shutting off), but the error code though persists. A random person I sold some parts too suggested I see if the magnet in the filler neck/vent valve still works and to replace if not. Are there any other suggestions you all can think of to remedy this issue?

P0234- Oddly I will get a check engine light with this overboost error when getting going again at low RPMs from a dead stop. At highway speeds, the CEL will be escalated to a ABS/PSM error when getting on it from say 55-75/80 mph. I recently heavily lubricated both waste gates (corrosion-x), cleared error codes, and had the errors pop up again. My next step is to replace the N75 sensor. If that doesn't fix the issue, I plan to lower the motor and replace the vacuum lines to the turbos. Any other tips/tricks here to help figure out what might be causing this overboost? Full disclosure, this car did run a Cobb stage-1 tune (I think) but is currently running a stock setup.

Any help/insights/suggestions would be greatly appreciated. I'll be sure to follow up to share outcomes during this de-f*&king process.

Scrh1

I’d pick up a durametric and get additional detail etc. I’d also look in to boost leak testing. I like markski’s videos and solutions he offers. Plenty of options and guides out there in the forum. Here re some links I use to help in solving the issues….

https://www.markskituning.com/pressu...d-boost-leaks/

https://rennlist.com/forums/996-turb...-question.htmlhttps://rennlist.com/forums/996-turb...pics-help.html
Pretty sure you will find the common culprits and all parts needed are in the posts above

happy boost leak hunting !

Kevinmacd

Might be the boost control valve.

aspiringporsche

This is great feedback.

I do have a durametric, but the code readouts are not any more specific. Still trying to learn how to look through engine details to see if I can diagnose the specific problem better.

I plan on doing the N75 this weekend. Fingers crossed and stay tuned...

theprf

All the hoses to the N75 valve should be tightly connected with no leaks. If the short angled hose that leads from the Y-pipe to the N75 is cracked or disconnected you'll get overboost. You can apply pressure to the hose that heads through the engine and splits to the wastegates. The "T" piece that's way inside had cracked on my car and was not delivering full pressure to the wastegate actuators.

aspiringporsche

This is great. Thank you!!!

Scrh1

One more helpful diy guide I found to replace the diverters / f pipe and such. Once y pipe is out you can replace the n75 and plumbing associated.

https://www.vividracing.com/pages.php?pID=68