Ford Quick Tips: #53 Deciphering What's Causing Your Lean Codes P0171 P0174 

I’m having the long fuel trim stay at 29.69, constantly. No fluctuation. O2 sensor replaced with no change. No vacuum leaks that smoke can find.

This man simply is a flipping GENIUS I don't have any other word for him HE'S A GENIUS keep these coming PLEASE

I've only owned and driven Fords my entire life and Im glad to finally see this. I live in the Denver area and when they do the winter blend at the pumps, a lot of my Fords have thrown lean codes. I replaced intake gaskets and a bunch of other stuff on my 01 explorer sport and it kept coming back so I sold it thinking it was a lemon. Then I got lean codes on my 06 NA mustang GT, my 97 mustang GT and then finally on my M90 roush Mustang GT before I put 2+2 together to realize it had to be fuel. Now if I get a CEL and pull the codes, I check the time of year and if it's late fall to late spring, I disregard it unless there's other codes or performance issues.

Ford tech you have ANY CLUE how many headaches you have saved me SERIOUSLY I might be able to sell my stock in asprine thanks to you A MAJOR MAJOR THANK YOU FOR EVERYTHING

Great tip about checking the engine load in the freeze frame data. You're spoiled with having a factory scan tool. That think is fast! It's pretty user friendly too by the looks of it.

I had an F150 with lean codes, and a weird noise from the engine intermittently. I think I sent you the video once I figured it out. The previous shop had cross a PCV hose and Vacuum line. It was the craziest noise. Fuel trim was all over the place, it was a tricky one.

98 f150 4.6l ltft at around 30. Truck runs perfect. Smoke tested and no leaks. Cleaned everything that could be cleaned. Still get p0171 p0174 codes. TOTALLY STUMPED on this. Saved this video so I can specifically look at those readings.

this dude is dedicated,thats all i gotta say, all the best in 2016!!!

I had those same codes on my 2004 Lincoln Navigator.. local shop wanted me to leave it there to diagnose, didnt leave it there... I opened up the hood and started looking for any anomalies, and found that the PCV elbow hose up top had a burned hole on it and air was leaking out of it.. long story short, I went to Advanced auto parts, bought a PCV hose kit and replaced that elbow, check engine light went off and wahlahh... !!!!

Sitting poolside diagnosing :) Happy New Year!

i have an 08 explorer Eddie Bauer 4.6 and have been fighting lean faults like crazy. every time i replace a part, which has been pretty much all the ones i can think if, i short the disconnected - to the + as you've shown. Today i replaced the throttle body. I now have stft at 42.2 on both banks and Ltft at 25 on both!!! Ive replaced everything i can think of in fuel/air and evap😢😢😢 The numbers do cone down some at highway speeds

On my 96 F150 with a 5.0 it was a dirty MAF sensor along with a major exhaust leak from the passenger side manifold to downpipe flange.

Hello, my name is Rex. I have both codes on my truck but also have driveability issues. I have replaced all 4 o2 sensors, MAF sensor, looked at the FRP sensor because it had a code and fuel pump signal out of range took me to looking at the fuel pump module. I think we spoke about this on another video you had, not sure if that was you. Anyways, I found the positive battery terminal was very loose, the IMRvalve was unplugged and the fuel pump module had the control wire exposed with an open piece of copper. I plugged in the connector for the IMRC valve, tightened the battery terminal, taped the signal wire on the module and cleaned up the ground to frame connection. IMRC valve now works. I reset the codes, and waiting for the truck to finish the drive cycle and set a new code for lean condition. The truck runs good fuel trim, after MAF replacement, now at idle, but any throttle raises the fuel trim up into the high twenties. You mentioned changing the FRP sensor but I have 40 psi on fuel line, so would that be something I should change even though I have good fuel pressure? Second question is, of course, what else should I look at for this lean problem? It is on a 2006 F250 5.4L 3v. Thanks Is there a part two to this video? I would be interested in watching the fix for this vehicle.

Beautiful work of my friend

Can you elaborate how the BARO reading will help diagnose a skewed sensor reading? I noticed you were monitoring it, but i must have missed how that helps aid in the reason behind the lean code.

Your videos are excellent. I just had my f150 5.4 in the shop for the past month having the VVT Solenoids, oil pump, both cam phasers chains guides and tensioners. I got my truck back only to have it return 3 days later for loss of power. The shop replaced the cam phaser and the VVT on the driver side. I had the truck for 2hrs when I got the loss of power and now its reading codes 0171 and p0022 after all this waiting for my truck to be fix and having to take it back overe and over has caused me to lose my job. I could use some advice. I would apprecatiate it and God bless

thanks a lot for this!! My check engine light on Expedition 03 has been on for months because of the P0171 & P0174 codes. I've changed the fuel quality to supreme (chevron) & it still hasn't turned off. I'll unplug the battery next time I pump to see if it helps.

i have a question bud i am the proud owner of a 2010 f150 4.6 i love my truck looks everything but one problem that i do have is that at exactly 50 mph the truck starts to just i took it to a shop n i told them about it n the rotated my tires n stuff n said that was going to fix it but it didn't any ideas what might be

I just had the p0171 and p0174 on a 2001 f150. You said its not common for "gasoline powered vehicles".. Mine ended up being the fuel pump. How would you differentiate between the pump and/or filter?

Hi MaK, I just bought a F150 5.4L 3v out of Las Vegas, It coded P0171 and P0175... runs like crap. So im having it transported by 8/15. I heard you say ur in AZ. can you help me diagnose properly? Oh by the way all you vids are pocket, life and vehicle SAVERS!!!😂

Excellent tutorial

Why wouldn't you consider Fuel delivery like a bad pump or dirty fuel filter? Will your scan tool monitor fuel pressure?

Thank you for your tips i have a 2005 ford 500 ltd and my outside temp is not working right it is 33 degrees here and it says 41 and it will also never go below 40 and it jumps to like round 68 70 when warmer i found it but don't know how to get to it it looks like a metal is riveted into the the front of car any suggestions

Thank you Sir. For sharing your experience and knowledge with us. Keep up the good work. God bless.

could this issue also be caused by a dirty or bad fuel injector? or would that set off a cylinder mis fire code ?

what can cause plus 3-4-5 range short term 1 and 2 like in this vid, but the same plus 3-4-5 range long term 1 and 2? had a slightly rough idle in my 2005 Escape, put all new (Motorcraft) plugs and coils, new upper air manifold gaskets, and a new PCV, but the engine idle is even more rough, 0 misfires on all cylinders, and can't find any vacuum leaks (used the carb spray method and checked every line/connection), upper air manifold had oil film inside just like the old PCV, and also had a faint smell of gasoline, thought original EGR valve is stuck open and tried to replace, but can't get the 1-1/16" fitting underneath it to budge, idk what else it could be, idles rough cold, hot, in Park and in Drive at a stop 🤷🏻‍♂️

Whats up Makuloco Got a few questions for you I have a 2005 Ford E250 4.6 with 144,000 miles on it. Truck runs great never had really any problems with it always brought it in for its regular service maintenance . I’m an electrician and I am very aware of the know-how of working on engines as well not as my profession but I have the knowledge to understand and repair. I’ve been receiving the two lean codes P0171 & p0174 Bank one and bank two. Originally the truck would correct itself and the service light would turn off then a few days later it would turn back on. Now it’s at the point where it still runs well I’m not seeing any issues with lack of power I change the spark plugs the coils and power seems to be great. I do get the lien codes both of them when I reset them in about 15 minutes pretty quickly now and it stays does not correct itself and turn off. I check for vacuum leaks I did not do a smoke test which would be really the right way I believe but I don’t see any vacuum leaks hoses all looks good could it be a failing fuel pump although the truck is running pretty strong. Where can I check or could it be a really small vacuum leak is it that sensitive to find something very very small would appreciate any of your feedback or help thank you so much Brent

grateful information,am waiting next video,thanks lot

Hi there love your videos, very well done and informative. Wondering if you would do a sort of buyers guide to F150's. Hesitating between 2004-2008 and 2009-2014 generation. Is there a real advantage to go newer if trucks have similar mileage? Other things to look for or check before buying, especially in higher mileage trucks? Thanks! Keep it up!

Great video as always Brian.

My 2003 king ranch 5.4 is bogging under load but idles perfect? Been working on It for a week now . Any ideas ?

I'm lean at idle o2 looks good. Mass air flow barometric is 154 Hz and 27 ihg I believe. Is that low? If so my mass airflow is bad? What else beside vacuum leaks should I check. Thanks in advance

Thanks you for posting. I might have to invest in a code reader. Does anyone know if FORSCAN can do this?? My 01 expedition had been a pain in the arse with this P0174. I replaced the fuel filter a few months back and I've already replaced all the ignition coils and spark plugs. I went to smog it and the mech told me that it had a permanent P0174 code. I checked for leaks using smoke. Nada. I let the O2 sensor sit in some SeaFoam overnight and the code changed from permanent to pending. I cleaned the MAF. I checked 3 of the 4 injectors (the 8 cylinder one is almost impossibru to reach, so i skipped it) and they were in spec. I'm suspect that the upstream O2 sensor is the culprit (the one I SeaFoamed). I think if it was the fuel pump, I'd get a P0171 code as well, wouldn't I? I'm tired of throwing money at it but I guess it's cheaper than a recurring car payment. Still, I'd like to finally nail what the actual problem is. Local mechanics seem to do the same thing I'm doing: guess. Hell, i can do that. At this point, I only have the MAF and O2 sensor left to replace. I believe they are both original parts so maybe one is just dying a slow death Thoughts?? If I replace these 2 parts, and still get the code, I'll have to go to the mechanic for sure (I have to smog it after all). But what could I have missed??

Aloha's Brian t- That was an excellent video! I can only imagine how far you could have gone with more tools at your disposal. But honestly and in this case, I really don't think you really "needed" any other tools. That said in guessing mode, it would be great to get customer feedback a few weeks down the road to see what has transpired.Thanks Huge for all of your videos. Keep on Keeping On. You are Top of the Mark. PS - Let us know about visiting Hawaii. Want to make sure our plans jive. ;)

Hello, I have a 2015 Mustang GT. I have 3 codes, PO 171, 174 and 454. Car has 14,850 mi.

I have an 03 explorer 4.6.. both banks are lean. light rough idle and when you gun it it doesn't go as if it's not getting enough gas. done tune up, egr, fuel filter was clogged so I swapped it. there were no vaccum leaks.

Fuel pump failures are very common. Just not on ford lol

Arizona! My home state

06 F150 4.6 tossing P0171 P0174 -FF , diag tree points to H22-24 and wants to see alcohol content % . My older autel for the life of me could not find the PID on scanner, even in mod 6 ? This particular truck has been tough, intake leaks both vacuu m and coolant for who knows how long, fixed those and new plugs and the truck ran worse than before. CLeared KAM but im always doubtful what exactly the autel controls. Slowly getting better. It at least finally passed the I/M readiness monitors. Any tips PLugs, filters, clean TB, Fuel psi good, no volume test ?

Close to what I'm getting on my 2014 F-150.....P0172

sorry about this unrelated question. have a 15 f150 3.5 eco. just got a hill assist/advance trac fault. didnt feel anything wrong and fault reset after a key cycle. any advice would be great as i am going to take it into service in a couple days. i like knowing a little before i talk to the service adviser. thanks

I just bought an innova 5160 scanner it's awesome 400 buck's autozone

HOW DO I CHANGE VALVE COVER BOLT GROMMETS ON A 2006 FUSION 3.0 V-6?

Fuel quality, really? Before I recommended a customer purchase fuel additive I would borrow a fuel pressure gauge from the local auto store and check the fuel pressure to make sure it is in specification. With fuel quality, you will have the same issue at idle as you would at half throttle. Not so with the fuel pump/fuel pressure.

I wish I had this when I was working on E-450 cutaway buses. I used to work for AVIS in Dulles. They had shitty ass bus & always wanted something for nothing. I used to have lean codes all the time but didn't have a smoke tester on site for me & wanted it fixed right without the proper equipment.

Hey FordTechMakuloco, unrelated but should I run a full synthetic in my 2012 F150 5.0? Any other major issues I should be aware of in that motor, besides the normal direct injection issues?

Hi Brian, I have a 2002 F150 with the 5.4. I am chasing an intermittent P0171. I hooked my scan tool up and the STFT & LTFT go sky high. I've replaced the fuel filter, cleaned the MAF, replaced the DPFE. I have no drivability issues, but the intermittent code and the high fuel trims are bugging me. I always use Top Tier gas. Fuel trims at times at idle approach 25+ combined, and drop to around 15+ at engine speed and continue to drop at higher engine loads, like heavy acceleration. Any suggestions? :)

can you do a video on a car running rich

if only I had a damn scan tool

Could a lean code at higher rpm b a dirty ,as air flow sensor. It was on a Corolla I just did.

what scan tool do i need

2013 Edge 3.7 p0171 p0174 no vacuum leaks mas clean any ideas

I noticed your MAF was reading higher than mine. I've been having rough idle issues, BAD gas mileage and a p0442 small evap leak. My MAF reads 0.7 to 0.9lb/min at idle. It's a 1998 ford f150 5.4 liter. Does it sound like a bad MAF? 244,600 miles. Original o2 sensors. I know I know lol, but I haven't had issues with the o2 sensors or with the truck until now.

...how bout a video on annoying intermittent misfires at idle that arent setting a code lol.

Why cant i find a way to check this stuff without a 2500$ computer :/