P0171 System Too Lean bank 1 Chevy Trailblazer "Fixed with no parts"

[@FlatRateMechanic]

Things I needed in this video. Smoke Diagnostic Machine amzn.to/2tbEMoe Mass air flow sensor cleaner: amzn.to/2HbyNJm Air filter and tune up kit: amzn.to/2vt1pbA The one tool every mechanic should have: amzn.to/2FN2r70

[@robertclark9235]

The Flat Rate Mechanic

[@robertclark9235]

The Flat Rate Mechanic b

[@eduardoflores3455]

P1200

[@smurf13w17]

Would this cause a vehicle not to get thr correct gas mileage? Example tank says 430 miles to E but in reality you get 380 miles to Empty?

[@KTHKUHNKK]

Excellent buddy I did subscribe I hit your thumbs up. I wish my fix would be easy like that. Very good video buddy.

[@bgtoups]

Thanks for a very clear method for diagnosing a problem and demonstrating how to verify and confirm the fix. Great video.

[@FlatRateMechanic]

Thanks

[@MitchGeddes]

Saved me a trip to the shop. Had that hose unhooked on my Envoy as well. Big thanks!

[@FlatRateMechanic]

Cool. Glad I could help.

[@jackbrown3270]

CHECK YOUR O2 SENSOR BY THE MANIFOLD!!!! that fixed my light even tho the code says to replace maf sensor

[@islandbeaches395]

O2 sensor bank1 I replaced the exhaust manifold gasket had a leak cause p0171 and damaged 02 sensor and caused the exhaust to flex and vibration in my ass lol

[@joeyfogderud2858]

08 Envoy 4.2, same code. I watched this video and I checked that same hose and guess what, that same hose was hanging off lol. Same problem. I just bought vehcile so previous owner left it undone.... I saved money as well, which is the best part!!!!!!!!!!

[@FlatRateMechanic]

Awesome glad video helped out.

[@casey7223]

Exact hose loose on my 08! THANK YOU for this quick video, I know this is not the fix all the time, but helped in my case. Cleared the code, now time will tell.

[@Savage7mileKilla]

The shop probably left it like that on purpose to keep the person coming back spending money.... a lot of these shops don’t want you to have your car running right they greedy

[@BradSavoie46]

"that will be $200."

[@Mime619]

Mine kept surging on start up to 3k rpms and slowly made its way down before stalling. Guys, don't go buy a smoke detector. I literally hooked up a hair dryer to duct and blew smoke into it. Plugged the other end next to it with a neoprene glove. Worked really well. I located the problem instantly. It was the resonator plug on the right with the metal strap. It was warped and put on wrong. $53 at the salvage yard for the new resonator.

[@ibraahimahmed9130]

I really appreciated the free information mechanic was trying to change me 300 I watched your video did it myself thanks again

[@JohannesC-c9k]

Good for checking the oxygen sensors too because they are providing feedback once the vacuum leak is fixed by the short term fuel trim going negative.

[@wayne19703]

Fixed my 2004 silverado quick thnx to you. It was hose on passenger side valve cover going to intake ducting behind mass airflow..

[@GaryW48]

My 'Check Engine' light came on just tonight. In called OnStar and they gave me the same P0171 code. At least I know what to expect when I head in to see a mechanic in a couple of days, and not be fleeced for $$$.

[@scallen3841]

I have the same code on our 2003 Chevy venture mini van , the intake manifold gasket was replaced 3 months ago . Dam that engine compartment is tight " 10 pounds of shit in a 2 pound bag " to look for vacuum leaks .

[@bonniejohnson1518]

i wish they would go back to making real automobiles again....simple is actually more advanced.....

[@theone-jm3gl]

This guy is all over the place..geeez

[@MsOblivius]

IF the 0171 code means bank 1 only it wouldn't then be a dirty fuel filter or failing pump would it? Wouldn't those cause a 0174 (bank 2) or a generic (both bank) OBD code since it would affect all the cylinders? Thnks... great service and video... I have an '04 explorer... Dont have a smoke machine... Grateful for any answers...

[@davidg813]

All these diagnosis people should say right away the very first thing with the p0171 is to check your gas cap and make sure it's tight. that's what I did and that was the problem. I lose gas cap will make your engine computer think your fuel pump is weak or your filter is bad causing the error code for lean bank

[@MrRusell86]

This concerns the P0171 code and here is my story for my 2000 Corolla. The code is triggered by the LTFT reaching as high as 38%. STFT stays in the normal range. I have changed the MAF sensor and the upstream 02 sensor. The car's fuel economy is fine and the engine seems to run fine as well. A mechanic said he hadn't seen such a high LTFT reading before and speculated it was the car's ECM. But in talking with a mechanic friend, he was fairly doubtful it was that. When I recently replaced the 02 sensor, I disconnected the battery to give the system a fresh start. STFT and LTFT started off at 0% but within about 20 minutes of test driving the LTFT was at 19-22% and then not too much longer after that it was back in the 30% range and a pending P0171 code came on in the system. Might it actually be a vacuum leak? Or could the ECM be the culprit? The car is due to be smogged in April so I kind of need to get this figured out.

[@martinanaya4009]

Thank you found a cracked tip of a Egr vacuum hose easy fix save me a lot time and money

[@Num1981]

My 02 trailblazer that stalled on me. Had to get it towed because it wouldn't start back up. Got home, scanned it and got the same code. Hopefully it's a simple fix. Probably not. Have to wait until my mechanic gets back in town to further diagnosis it. But until then, I'll check there hoses and clean the sensor to see what I get.

[@FlatRateMechanic]

Bummer, unfortunately it could be a number of things. Typically the hose I found off on this one doesn't just fall off someone was probably checking the air filter or working on it at one point and left it off. In your case it's a good possibility you may just have a bad mass air flow sensor or a large vacuum leak of some sort. But with a p0171 there are a number of different possibilities

[@ralfsautomotive]

Nice Video but Fuel Trim right at zero is a big statement LOL never seen on at 0 before. Just cutting up!

[@TerryB751]

Interesting. Recently my 2015 Malibu had a check engine light on (code P0171 showed up, no other codes) - engine was running fine, no symptoms. The engine is 2.5L DOHC, 4-Cyl. with 64,400 miles. The dealership did a visual test and smoke test and spent 5 1/2 hours on it. Couldn't find a thing and eventually reset the check engine light and gave the car back to me. They told me if the light goes on again, bring it in and they'll continue to work it. They mentioned it could be a bad sensor reading. They didn't know at the time and so it was inconclusive. A lot of time to spend at the dealership for nothing, unfortunately. Since they couldn't find anything, they didn't charge me, otherwise it would have been $199.

[@FlatRateMechanic]

Well I'm glad they didn't charge you adleast. Its not uncommon for cars to set lean codes for unknown reason sometimes. Usually a result of a mass air flow sensor getting some dirt on it in most cases. Just be grateful they didn't charge you for something you didn't need. See that all to often. It's a shame and a lot of the reason I started this KZbin channel so not everyone has to feel like they are at the mercy of there repair shop.

[@TerryB751]

@@FlatRateMechanic Found the problem. Just needed to put gas in from a different gas station than I used before. (Same octane). When I took the car in to Tires Plus for the P0171 code analysis, they couldn't find anything wrong either but gave me their list of culprits for the code and one was "Fuel Quality". After filling up at a different station, the check engine light went out after a day or so.

[@FlatRateMechanic]

@@TerryB751 Nice, thanks for the update.

[@willypheelerup3623]

My 04 3x4 LT is running so rough. Felt like the plugs replaced still shitty. Checked coil packs...good maf sensor good.. But now I'm also blowing fuel pump relays now. Can't figure it out because now It won't run an obd

[@-MrRichBiker1967]

Yo... You are an awesome mechanic,

[@ALLINCAPZBANGINONWACKZ805]

HEY GUY (PLEASE MIND NOT THE CAPITALIZATION. I HAVE BAD EYES) I HAD A BRAND NEW MAF SENSOR INSTALLED IN MY VEHICLE. LIKE A COUPLE DAYS LATER I TRIED GETTING A READING AGAIN. IT SAID NO PROBLEMS BUT THE NEXT DAY THE CHECK ENGINE LIGHT CAME ON AGAIN. THEN I CHECKED THE SCANNER TO IT AGAIN AND IT SHOWED THE SAME CODE WHICH IS THIS ONE. ANY SUGGESTIONS WOULD BE GREATLY APPRECIATED💯 THANKS IN ADVANCE

[@YH7R]

Great detailed content GOD BLESS

[@kyostipoysti1036]

Hey awesome video. I need your opinion. Basically my car runs fine but it throws the P0171 code and I have replaced everything from spark plugs (original ngk ones) to oem ignition coils (previous ones were faulty) to engine air filter, to cleaning out the fuel injectors so I can rule out coils, injectors, spark plugs. I am chasing goose here I don't know what else to do as I have cleaned my MAF sensor using the cleaner spray and put it back in. I am not sure I even replaced intake vacuum gasket seal. I just don't know what else is causing that code? Could it be fuel pump or some other vacuum leak somewhere? Or could it be o2 sensor? I just don't want to be wasting anymore money fixing things that don't really solve the problem or get rid of the check engine light

[@i_am_not_1_of_them903]

Same situation I’m in

[@tdw5933]

Another thought, appreciate it.

[@Gen01Lee]

Thanks was exactly the problem.

[@Gen01Lee]

This temporary fixed the issue. I’ve tried everything from VVT solenoid, MAF, spark plugs, wires, gas cap, cam sensor, crank sensor, vapor box in the rear, air intake gasket kit. Only thing that helps is fuel additives and high octane gas to get me through emissions. Then it comes back on eventually. I did read it could be a loose timing chain but I would think it’d be something more simple. Wish I could figure this thing out. Lol

[@JonniArmani]

First thing you need to do before you do anything else just make sure your gas cap is tight- and is sealing properly.

[@jarredjones2862]

What else can I use if I don’t have the smoke machine

[@KhmerUSA999]

but my car is opposite from what i saw in your video ( short term FT is 11% and Long term FT is 0.8% ) why? thanks for help.

[@MrMDee-si1bz]

Great vid! Thanks for sharing! 👌🏻

[@robertnunez5036]

i hve a po171code dont know if ill fix it however you are a great teacher.

[@FlatRateMechanic]

Thank you!

[@robertnunez5036]

i did fix it,it was o2sensor,what i did is i swaped right to left and left to right and code went to opposite side.

[@ConservativeWatchParty]

My e90 is making a loud shinning noise with error code 171. When I release the oil cap, there's lot of suction and resistance to release it and once the cap comes off, the sound disappears. As soon as I put the oil cap back on, the loud noise comes back. What could this be? The code from Autozone says it's the MAF but I changed that 6 months ago and it wasn't needed so I returned it. I also have ISTA but I'm not sure how to use it for this.

[@atomicdmt8763]

How would this affect just one bank? There are 2 banks on this vehicle, correct? Thanks

[@ProjectCarTV]

Good video

[@teevasquez1222]

I have a question can you purchase any can of smoke so i can run into mas flow senser to see if i have any air leaks anywhere

[@christianbuckner1]

Got this code, reached behind the valve cover and found the pcv hose loose. Replaced with new hose. Code has not returned at this time

[@kowal116]

Hey. Superb video. I have strange problem with short fuel trims. My engine is BMW M54B30. On bank 1 i got +25-28%, but on bank 2 it is ok 0 to 5%. I know that my oxygen sensor after cat on bank1 is dead. Is this can affect on fuel trims? MAF is working, I checked rubber hoses and there is no cracks. Help please. Thanks.

[@winslow69]

No. Pre cat 02s only affect fuel trim. The 02s behind the cats are to measure the efficiency of the Cats by comparing their readings to the first 02s

[@luisalejandrojorquera3177]

Very good video thank you

[@thebunkertv8847]

P0171 engine vacuum leak or bad mass air flow sensor or o2 sensor . Running lean bank 1 bank 2

[@makepeace2850]

Wow very informative thank you.

[@FlatRateMechanic]

Thanks

[@jeffyoutube8648]

Thanks for these my car got fix

[@alexnguyen8025]

Hello I have a Toyota Corolla 2000 which is the same problem ( po171 and po302) , what should I do ? Change the intake manifold seal ? or change the spark plug cable for it ? Thanks for your video. It's pretty awesome. I have learnt something else more about it.

[@FlatRateMechanic]

I would suspect a bad cyl 2 injectors. But hard saying there is a lot to it.

[@MarcoPerez-gm7pi]

Inition coil

[@bornjamerican52]

🔥🔥🔥🔥 hit the nail on the button

[@joaquinaguirre2976]

Thank you so much! good video, I will do the test myself.

[@WV591]

if only it were that EZ in real life.

[@richb5478]

I started putting Marvel Mystery fluid in my gas tank every time I fill it up I started getting that code engine running too lean so I stopped adding the Marvel Mystery fluid and the code went away and never came back

[@FlatRateMechanic]

That does not surprise me, fuel additives and definitely throw of fuel trim values. Cars are very picky nowadays.

[@richb5478]

@@FlatRateMechanic thanks that's good to know!!

[@sir_cap1734]

Can e85 cause this code too ?

[@tonyayala7086]

Fuel injectors cleaner caused that code to my vehicle

[@alexs3318]

I use stp stuff in a red bottle. Works well. Makes it run way smoother.

[@DIRTDIVER882]

Thanks for the video brother my 2001 yukon xl is doing same thing. Conveniently a day after valvoline did my oil change??? Im thinking they did something similar , hopefully its as easy or close to it to fix. Only thing is i had a 02 heater code pop up after the initial lein code?.first it was bank one sensor one, cleared it. Then it was bank 1 AND 2 lein. Cleared it. Then it hit me with a bank one sensor 1 heater switch?? If u get around to this comment, what do u think?

[@FlatRateMechanic]

I would keep clearing the light until you get something consistent before chasing you're tall. Sound like the computer is a little confused. You can also look at the fuel trims on a scan tool to see if it is really running lean. If your fuel trim is anything above +10% on eather bank you probably have a problem some were. Fuel trim should always stay around 0 at idle if it taking away fuel, like -10% that would mean its running rich.

[@savvyguy4180]

I got a new mass air flow sensor on a chevy aveo LT it's still running lean

[@bassb450]

So most of the times when you get a lean code you have a vacuum leak? And those fuel trim figures on the tech 2 are at idle correct?

[@FlatRateMechanic]

Yes and yes. There are a # of things that can cause a lean condition or a p0171 but yes most common cause would be vacuum leaks.

[@Queensni99a]

How can you check without a smoke machine

[@mark.r8900]

Great tutorial. My 2007 audi a4 giving a p0171. The car starts fine and idles around 1200 rpm then drops to 800 rpm and shakes. I unplugged the brake booster hose and the rpm stays same no change. Shouldn't the rpm rise because I am introducing more unmetered air? I am totally confused. Any help would be greatly appreciated. Thank you

[@cristiangarcia3296]

Did you fix it??

[@angelf9800]

What can it be if I see smoke around the Throttlebody can it be the Intake manifold or Vale cover, my short term FT is -5 and then goes up to 8 then back down to -3 and long term is at 18 and have a code P0171 lean code

[@electronic7979]

Useful video

[@Rforce78]

I have the 4.2l6 in my wife's Buick rainier and it have been going dead for no reason and not throwing any codes for 2 3 years and the other day I finally get a code pop up and it's this one, will this be the problem causing the engine to just die wile sitting at a red light

[@18MoreGolfShop]

What if I have the same code and also did a smoke test. But did not find a leak during the smoke test. What else should I be looking for?? 07 envoy here. Same code

[@thehammermanduke]

Thanks for this info😊

[@kevinlewis8642]

Curious why you didn't show the freeze frame.

[@FlatRateMechanic]

I didn't need to in this case. It was very clear it was running lean at idle and it was easy to verify the problem. Freeze frame can be a very valuable tool in finding hard to duplicate problems. It this video that was not the case

[@jfleck1171]

Thanks for this, it's exactly what was wrong with my envoy

[@jarredjones2862]

Love this video

[@contentspy7477]

Finally a good explanation!! Cheers

[@justingillis6150]

just put a volant cold air intake on 05 tahoe... the main air intake tube will not sit flush on manifold. do you think this is why I'm getting these codes system too lean?

[@timmypstyle]

I keep getting p0171 on my 06 trailblazer along with long cranks before the engibe starts after its warmed up. Cold start it starts right up. Took it to my mechanic and he couldn't find anything at all even with the smoke machine. So he cleared it and gave it back. Now I'm getting it almost every time I start it, it drives fine, everything seems normal but I still keep getting p0171. My other mechanic buddy says maybe fuel pump or crank sensor, and online other trailblazer owners have said mass airflow sensor or O2. But my mechanic said he found nothing wrong. Any ideas? I have a code reader and had no clue I could look at fuel trims so I'll try that and see what it says. This thing is bugging the crap out of me.

[@hajrudinkavazovic2231]

Adjust the the lifters to 0 lash and you be good too go buddy

[@Gen01Lee]

@@hajrudinkavazovic2231 I have had this issue for years and tried everything. Crank sensor, mass sensor, fuel vapor box in the rear, VVT. If I use fuel additives and the truck feels like it the code will go off. But always comes back. I heard it may be a loose timing chain? Why do you say the valve lash is the issue?

[@ryanchristensen1799]

I've got p2096 and p2098 lean fuel trims bank 1 and 2. Before these codes were set I drove around fine for 6 or 7 miles and then my engine ran really rough and the stabilitrak light was on. I made it home about 5 miles away but the engine was running really rough and thought it would die on me. I pulled all spark plugs and they were fouled so I cleaned them all up and found out that that the pvc tube from the valve cover to the cold air intake was loose and barely in the rubber tube. I zip tied it back into place and re drove the vehicle and it seemed to run fine but I now have those two codes stored. Would this have happened during that first drive or do I now have another issue? Would old gas cause the issue after fixing the vacuum leak?

[@BryanG830]

Well, where can I find this on an 01 Cavalier 2.2l SFI engine?

[@johnlakesid3884]

Thank you for this.

[@RedArrow73]

That hose is the PCV. Re-connect right away.

[@DMJ160]

Flat Rate, what would it mean if the long and short term readings are opposite of the reading you got in this video? I have a 03 tacoma 3.4l with the p0171 code and my fuel trim readings at idle were 1.6 on short and -14.9 on the long. Cleaned MAF and checked for leaks by spraying card cleaner around intake and vac hoses. No change in engine rpm. I suspect weak fuel pump or clogged/bad injectors?

[@FlatRateMechanic]

Looks like that to me is a rich condition the computer is actually taking away fuel I would suspect a leaky fuel pressure regulator

[@DMJ160]

Yea, I thought it odd when I got the numbers using the scan tool. A lean condition means, too much air or not enough fuel correct? I did fuel pressure test and got 43 psi. I ruled out fuel pump and filter with that reading. I replaced the upstream air/fuel sensor. Truck seemed better but still had some hesitation punching down on the throttle. Then I realized I had a knock off Denso mass air flow sensor. I bought a real Denso mass air flow sensor and installed that. The truck is running like a top now! I am thinking , the mass air flow sensor was telling the ecu that , there was less air coming in then what actually was. In turn, the ecu was taking away fuel to balance it out. Excellent video Flat Rate!!! Thanks for the input!

[@FlatRateMechanic]

dave jones awesome. Glad you got it fixed

[@jasonbrown467]

@@FlatRateMechanic i have two trailblazer and neigther have mass air flow sensor, i googled it and i cant any one else talking about one for these vehicles. there is a air temp sensor in the intake tube thing between the air filter and the throttle body and a manifold air pressure sensor in the intake manifold. i wonder if you guys have unreleased gm prototypes?

[@clydeschronicles3462]

If I get p0171 and p 1150 at the same time

[@fofodiy]

My egr valve has a vent hole and smoke comes out of there is that a vacuum leak?

[@johnbrownlee7623]

Thank you, like an easy fix......................

[@socrown7075]

I got this code on my 1999 Oldsmobile Intrigue , any ideas? it make a funny sound when starting but it runs great

[@rwrobs777]

What were the LTFT on bank 2 ??...if the LTFT were say 22% the DTC for bank 2 (01074) it would not set a DTC...that would make me change direction as far as troubleshooting...."bank specific" vs. a leak that would set both DTC's....a leaking intake runner on 1 bank vs. a leaking MAF sensor bellows !!

[@shellybelle6781]

So I put a mass sensor on mine because I got this p0171 code . Check engine went off when I changed it. now it’s back on with p0171 code again. What should I do

[@rubbermallet3873]

great trick bro - 👌 thanks - 👍

[@yngsol]

I have a dodge and is doing this same thing I already replaced o2 sensor for both banks and nothing still please help

[@franchilstervil3587]

Thanks I wish I could use that smoke machine.

[@WeMessyTV]

Genius

[@thebunkertv8847]

Check to see if breather is unplugged

[@thebunkertv8847]

Vacuum leak or mass air flow sensor .

[@michaelsharp7611]

It could also be a clogged fuel filter

[@user-df8nw3jg4b]

I had both both codes both banks too lean and I replaced all o2 sensors and codes went away for about 6 months. Now they both came back on. Any idea?

[@FlatRateMechanic]

Lean codes can be tricky sometimes, I would really need to see scan tool data in order to point you in the right direction. Tipicaly if it's lean on both Banks it ends up be a vacuum leak or mass air flow sensor probably.

[@rankgts3962]

Brother i need a help please i got the short term -7 or -6 i think its good but the long term is 0.0 always!! Not change what is the problem please help and the engine little shaking with rpm ( nissan altima )

[@rankgts3962]

Maybe because of o2 sensor??

[@user-df8nw3jg4b]

@@FlatRateMechanic No vacuum leak found and maf sensor cleaned and replaced. Still having the same codes. I bought 20lbs of tanerite from academy. Going to throw it in the cab and grab my 308. That should do it.

[@frankteam1645]

hello Brother 😊 awesome video. i have same code in my car ‘mercedes b klass 2005. the error code is p0171 bank 1 . i had changed throttle body to be able to fix it. but no fixing . same problem is going on. My car is working unstable or continously moving forward and back in stable mode . sometimes it stop for a while . could you please inform me how i i am gonna solve this problem

[@tajhealthnature8570]

Nice video where you get these parts to fix it..

[@sonnykelley1259]

Maybee Santa will give you the parts for Christmas lol

[@rafalpanwojny]

alright sir youre good to go thatd be 400$

[@rondoschiavoni8840]

Can a fuel trim be mechanically adjusted on a Buick 2003 3800 V6 engine?

[@FlatRateMechanic]

No

[@bonniejohnson1518]

i wish they would go back yo making real automobiles again

[@bossgoon115]

Did you have the truck running while doing the test

[@FlatRateMechanic]

No

[@bossgoon115]

Thanks!

[@xpandax1993]

I fixed mine with a Carb Cleaner - $25 at autozone

[@shellybelle6781]

How long did you have to drive ?

[@chickenfriedlasagna4597]

@@shellybelle6781 Same question

[@queenmoebetter6470]

New Subscriber 4-2-22

[@mikehall9666]

I have a 07 impala ss 5.3 getting a code for bank 1 lean and then sometimes I get bank 1 rich code

[@Banjoandguns]

I got this code on a 2000 ford 5.4l I I could erase the code and it would drive ok. It turned out to be a unplugged fuel injector

[@MrHRPV]

That would also set a misfire code for the specific cylinder .

[@terrellscaife2411]

Cool 😎

[@edbegley1635]

will the smoke be able to pass closed throttle plates

[@norbittfernando3183]

Yes, because it is never truly closed/may have small hole(s) in it.

[@RickyPisano]

Is this a 4 cylinder engine with only one bank??

[@ikon1996]

Its an in-line 6 cyl, hense only 1 bank

[@thebunkertv8847]

Unplugged fuel injector possibly

[@fixorflat7845]

What I ended up doing is plugging that tube Because the trailblazers like to shoot oil into the throttle plate and clog it.

[@markrubio3756]

What was the problem?

[@Ilona_230]

Lean condition, more air than fuel in the engine

[@emilyknight4341]

I don’t want to go through the trouble of them not knowing the legit issue, when I know the initial signal was 02 sensor. I’m wondering that someone just left my shit unplugged or it’s dirty .. how can I tell ?

[@fyrfox2000]

Is engine in or off?

[@dangerousfreedom4965]

What motor are you working on 5.3 6.0?

[@oudude27]

4.2

[@FlatRateMechanic]

yes 4.2l

[@valdimicolchik7975]

6 cylinder in line (4.2 Litre)

[@DeplorableTexan]

What engine diagnostic computer are you using? Im using an Actron and yours is WAY better.

[@wild8757]

Can I borrow your smoke machine?