P0171 and P0174 lean codes

[HOGTRK]

My truck started sputtering and engine shut down. After 3 attempts I got it to start and keep idle. Later that day the check engine light came on and engine ran a little rough. I pulled the negative battery terminal to reset the computer. Truck has been running ok but occasionally has rough idle. I pulled codes with a scanner and got the same as you.
P0171 and P0174. Ran a diagnostic and scanner said both O2 sensors on bank 2 were registering zero or nada. I plan to replace both O2 sensors (after cat) on bank 2 to fix the problem. Will let you know how this goes after replacement.

[HiTechRecneck]

Just a word - the downstream O2 sensors only trip every few seconds and the voltage you will see is very low. Yours may not be bad.
Check for that vacuum leak at the elbow!!

[Black Molly]

My truck started sputtering and engine shut down. After 3 attempts I got it to start and keep idle. Later that day the check engine light came on and engine ran a little rough. I pulled the negative battery terminal to reset the computer. Truck has been running ok but occasionally has rough idle. I pulled codes with a scanner and got the same as you.
P0171 and P0174. Ran a diagnostic and scanner said both O2 sensors on bank 2 were registering zero or nada. I plan to replace both O2 sensors (after cat) on bank 2 to fix the problem. Will let you know how this goes after replacement.

Don't replace backs...just fronts and turn off rears in tune.

[DATS TTRAH!]

Sure hope this is an easy fix, well see!
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['02 H-D #677]

I think the most common cause is the elbow for the lower pcv hose.
It is at the very bottom of the lower intake. I just fixed mine after chasing it since December.
First off, it's a lean code, which means that when the ses light is on, the fuel trims are maxed out rich. Not good!@ Neither is lean.
Because of age and engine heat, the thing just basically rots.
You almost have to pull the sc to replace it, unless you have tiny hands and are a contorsionist plus being double jointed.
Did mine in about 3 - 4 hours counting painting the intake and sc.
You can't see it at all, just feel it when the sc is off.
Here's a shot of the old (broken in two) and the new elbow.
The entire hoses, junctions etc are available from ford.com
It's a cheap fix - mostly your time to pull & reinstall the sc.

This should have been an engineered/maintenance consideration from the factory ... an extended barbed hard-line!

[DATS TTRAH!]

To the guys that had this PCV line as their problem......did your truck ever idle high before you made the fix?? this would be a major help before putting my hands on Friday. I'll know to get this plastic line before I start pulling off my whipple for the plugs and cops.....?


Thanks!


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[DaygoHD]

so i cleaned the MAF again and the damn thing is back!!!!!!!!!!!!!!! Can some one please help !! i have a K&N system and ive heard it could be the oil from the filter... but i want to know if i need a new cone, new intake, new maf or is there something else that could be wrong with my truck? I mean is there sometthing else this bank 1 runnin lean code could mean?

Same exact thing happened to my truck. I think it's very common problem when these trucks come into age. Replaced the elbow (as HiTech mentioned) and the MAF; problem went away.

[HiTechRecneck]

Vacuum leak will indeed cause a high idle speed!
Wish mine would have done that - it would have been easier to find.
That elbow seems to rot from heat etc. on the back of the intake.
You can't see it, but you can reach it to replace it.

[DATS TTRAH!]

You think u could post up a picture to better direct me bc I coulda sworn everything I can see, I checked.

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[Black Molly]

You think u could post up a picture to better direct me bc I coulda sworn everything I can see, I checked.

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you actually cant see it that is the problem...if you follow the vac line off your passenger side pcv you will see it goes to the plenum...in the middle of that is a T that is the line that goes to the back of where the elbow is located...basically you have to take off your blower to get to it..at least with my meat hooks

[DATS TTRAH!]

Awesome! I can totally understand where now, Thanks for the explanation!


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[HiTechRecneck]

It's not hard to do - just impossible to SEE!
Your truck will love you for fixing it!
Lean = NFG!!!!!

[DATS TTRAH!]

NFG?


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[HiTechRecneck]

NFG = No Frickin Good

[HD4mula]

Have had these codes for over a year. Once I posted here and nada. Glad to see some options to check.