Welcome to the North American Subaru Impreza Owners Club Friday July 10, 2020
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Technical > Engine Management & Tuning > AccessPort

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.

* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Thread Tools Display Modes
Old 05-28-2019, 02:19 PM   #1
Scooby Newbie
Member#: 46936
Join Date: Nov 2003
Location: Atlanta
2004 WRX

Default ap for cel diagnostics

Got a V3 form my 04 wrx, no recent changes to car, started throwing p0171, but no performance hit is noticed.

can the AP help me diagnose more accurately where I need to look? ( i have the p0171 thread queued up in another tab, but if this can tell me more then id like to know)
* Registered users of the site do not see these ads.

Last edited by Kanchou; 05-28-2019 at 03:20 PM.
Kanchou is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 06-10-2019, 04:50 PM   #2
Scooby Newbie
Member#: 502897
Join Date: Jun 2019
Location: SouthEast Wisconsin
2006 Impreza WRX


an P0171 should be Fuel Trim system Lean Bank 1. Our cars seem to be very prone to vacuum leaks that may cause this lean condition.

On the Accessport you can monitor your Short and Long term Fuel trim's, they are labeled "A/F Correction #1" and "A/F Learn".
After the vehicle is warmed up take it for a cruise (Freeway will be good). If the "Fuel Learn" Perameter passes +15% it will set this DTC.

If this is the condition your experiencing I would suggest looking for a vacuum leak after the Mass Air Flow Sensor and but before the cylinder head. The intake manifold gaskets are very common also so you might have some luck starting there. You can also get this code from an exhaust leak at the manifold, so don't eliminate that right away.
Smoke testing the intake is the safest way to perform this test but most people don't have access to EVAP leak tester that I happen to use personally, you can always use short burst's of brake clean while the engine is running on the problem area(s) in question and monitor the "A/F Correction" change then you will have found your leak.

Other common things are forgetting to attach something after you have worked on the vehicle, such as the Recirculation hose, EBC hose, EVAP hose, or PCV hose. Don't forget to check your boost guage and line/fittings if you are using an auxiliary one.

Just some ideas to try.
Justorymes is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 12:02 PM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.