terrible gas mileage & code p0171 - JeepForum.com
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > General Technical Discussions > Engines & Drivetrain > terrible gas mileage & code p0171

FS: Jeep Fog Light LED Bulbs! Several Brightness Options! SPARTAN LOCKERS are on sale BIG TIME at ROCKRIDGE 4WD!Yukon Ultimate 35 axle kit for c/clip axles with Yukon Zip

Unread 10-30-2013, 12:08 PM   #1
Registered User
Join Date: Oct 2013
Posts: 1
terrible gas mileage & code p0171

I have a 1999 Jeep grand Cherokee Laredo 4wd ... its throwing a check engine light so I went and had it read. The code is p0171 system too lean.. its says a lean air/fuel mixture has been indicated by an abnormally rich correction factor, right rear fuel system lean. The catch is my gas mileage is 4.6mpg (no joke) I have no clue where too start or what exactly is wrong.. can anyone help please & thank u

parrottlove is offline   Reply With Quote
Unread 10-30-2013, 09:54 PM   #2
Registered User
1988 YJ Wrangler 
Join Date: Aug 2010
Location: Chesapeake VA, Chesapeake VA
Posts: 512
Are there any other indications on the dash that are weird? Is the CEL and MPG the only indications you have? Does it lack power? Does it sputter when you get into the throttle? Does the thermometer indicate? Need more info.
'88 YJ with SOA and SYE and a bunch of custom crap from BWF in Chesapeake.
'97 XJ on 8" lift, double triangulated rear, long arm 3 link front, Eaton/60 with 5.14 gears.
GrouchyTim is offline   Reply With Quote
Unread 10-31-2013, 07:21 AM   #3
Registered User
2002 KJ Liberty 
Join Date: Dec 2009
Location: Colorado
Posts: 8,073
1st what engine,4.0 or 4.7?

Most common cause of that P0171(and/or P0174) is vacuum leaks.
'02 Liberty sitting on 35" tires,HP44,RockJock60,and AtlasII t-case
tjkj2002 is offline   Reply With Quote

Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.