Notices
Boxster / Cayman Porsche Boxster, Boxster S, and Cayman discussion board.

99 Boxster with P1124 and P1126

 
  #1  
Old 06-24-2019, 04:03 PM
Registered User
Thread Starter
Join Date: Jun 2019
Location: San Francisco
Age: 30
Posts: 1
Rep Power: 0
sosspistache is an unknown quantity at this point
99 Boxster with P1124 and P1126

Hey guys,

I have a 99 Boxster 2.5L which has has these two codes for a while. I've been reading a lot on these codes on this forum and other places and I have an idea of things I might want to try next but I wanted to brainstorm what would make the most sense with people here.

Here are some details:
  • 90k miles. Engine runs great, constant power delivery, no rough idle.
  • P1124 and P1126 always come back within a day after clearing codes, always in pair
  • Engine seems to run hot if the car is left running at idle, the temp indicator eventually crosses the middle of the gauge
  • The car fails smog with high NOX
  • I've notice some oil in at least one of the spark plug tubes when I changed the spark plugs a few months ago. It was for the cylinder closest to the cabin on the driver side (cylinder 1?)
  • No apparent excessive smoke
Here's what I've tried so far:
  • Replaced MAF. This didn't fix those codes but made the car behave a lot better (lot smoother power delivery, engine seems to run stronger)
  • Replaced gas cap. Didn't fix the issue.
  • Opened the oil filler tube cap with engine hot. RPM dropped and recovered shortly after as expected.

For next steps, here's what I'm thinking:
  • Replace AOS? The oil in the cylinder seems to indicate that the AOS might be bad, but the car doesn't smoke and the old MAF didn't seem particularly dirty when I replaced it so I'm not too sure if that would help. Any thoughts?
  • Air leak? The car seems to be running hot which might be due to an excess of oxygen due to an air leak, making the mixture too rich. This could be causing the high NOX causing the smog to fail too since the car is too hot. The car responded well to removing the oil filler tube cap so I'm not sure if that is the problem. I'm also not so sure how to diagnose that as a DIY-er - I've read about a few techniques like using soapy water but I'm not sure where to start.
  • Weak fuel pump? The engine is running lean so I either have too much air or not enough fuel. Any tips on how to diagnose the fuel pump?
  • Replace spark plug tubes? Maybe one of the tube is cracked and is causing the oil to leak through? There's no white smoke though so I'm not convinced of that.

Do you have any additional diagnostic steps I could run? I have an OBDII reader that I can consult. I've read that air flow should be between 13-15 for example. Is that right? Any other values I should monitor?

Thanks so much for your help!
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
SKY213
996
13
12-14-2013 07:11 PM
spg993tt
Boxster / Cayman
1
04-24-2010 06:53 PM
Desmo
Boxster / Cayman
4
09-06-2007 12:25 AM


Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:
You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: 99 Boxster with P1124 and P1126


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.