Check Engine Code p0171 p0174 . What you need to know. 

Not first! ASE 101! Cool video and explanation now I just need to get my eyebrows to grow back from that starter fluid! LOL!Where are my manners? Merry Christmas and Happy New Year!

Use carburetor cleaner spray to check for vacuum leaks -- not starting fluid. The diethyl ether in starting fluid is too explosive -- it will work, but it's way more dangerous than what is needed. Also make sure the carburetor cleaner is not dripping on ignition sources like spark plugs, coils, or plug wires, and make sure to let it evaporate between sprays so the engine is not soaked in case an ignition source is found. I once saw a Goodyear store manager trying to help save time on a service job by doing the engine clean (spray can engine clean) while the engine was running -- the flames engulfed the entire engine compartment & reached the open hood. We were lucky to be able to extinguish it without damaging the car.

I diagnosed a Toyota matrix 2005 model yesterday with a lean code p0171 and the upstream oxygen sensor was bad. In a case like this wat is d correct fix. I was thinking of a possible vacuum leak but I couldn't see any leak. I just want to know if replacing the O2 sensor is d right fix.

Excellent coverage of issues in logical order of analysis. Smart guy, and clearly experienced.

Hi, great video Question, Do I have to set/rotate engine TDC or no need to.? When smoke testing the intake manifold I get smoke out of oil dip stick & oil cap When removed cap or oil dip stick.

Thanks a ton , Salem !

Excellent video, very good and easy to understand what you are talking about! Awesome thank you and you rock! 😀 *****

Good video especially since I have a 2001 3.8 v6 Camaro. Got lean codes for both banks. Trying to figure that out right now.

Hello I have a 2007 infinity g35 and I have a p0174 code fuel system run lean bank 2 and my long stream bank 2 is 35.2 short stream is between -3 to + 5 and I have really bad gas mileage so I was wondering if u can help me thanks

Could a bad throttle body cause a lean code like a p0171

Great info 👍🏾

Ok, but heres the thing when it comes to my 97 gtp its been a ton of poor idling related things. In my case i believe my p01701 code. Leads me back to the intake manifold becuz of the mileage, pontiac cheaped out on that paticular gasket. And last but not least the elephant in the room when engine is running lean and its obvious to me its related to the gasket , the engine will begin to idle rough and then begins to jerk back and forth the engine begins to rock back n forth at times i need to hold the gas so that the needled begins to stay closer to the 1 where it finds its consistency . Although all the things u spoke about were all related this is a unique situation i found myself in.

I've had the P0172 pop up a couple times on my 01 Regal GS, haven't found any vac leaks, I already have the extra O2 that I bought awhile back. FP is good running a WB255 pump and 65lb injectors on E85. Gonna change the O2 and I'll report back. I've been told the E85 is tougher on the O2?

My 2003 Grand prix Turbo charged GTP code says that knock sensor in bank 1 is bad, I replaced both knock sensors and still gave me same code, Then again I replaced both sensors with factory recommended sensors, I get the same code and the engineacts like wants to overheat.

I have watched hours of video trying to narrow my problem down and you just helped more than most of them!👍

Good video just got done with lower intake job runs great I'm using a 180 tremostat its much better then the 195 thanks for all your help when I asked about replacing lower intake

P0171 code, smell of gas but when cold start it spudder rpm’s almost wanting to shut off but doesn’t do it everytime try to ready my fuel system status it says it can’t relying on 02 sensor

Very helpful

What about a loose connection at the muffler pipe where it connects to the engine..will this cause a p0171..?or bad exhaust gasket...?if someone worked on it and didn't tighten it good enough , or the gasket failed..?

So, I have 2015 Chevy Impala and my check engine light just came on. I went to the local Auto Zone and used their scanning machine and I got a P0171 and Po174 code. The guy at Autozone says I need a new mass air flow sensor. Should I just do that and hope that fixes it or should I try to comb through it a little more?

Very thoroughly explained!

I am in trouble help me out facing p0174 In my v6 toyota

My 1997 Chevy suburban stalls during acceleration I cleaned the maf sensor and codes p0131 p0171 and p0174 popped up. Also when Vehicle is in park I can accelerate and it runs fine but as soon as I put it in gear it stalls and when it don't stall it accelerates really slowly.

Salem, I'm having a rough idle, I replaced the LQ4 MAF and it seemed to smooth at least until the engine got warm then back to the bad idle. Don't find any vacuum leaks not that there isn't one? I do run E85 not sure over time will that kill a O2? Going down the track it's fine this car runs high 11's on a Gen V.

What if there is also a pO430 code involved to. You think a bad down stream o2 could then make it think an upstream is reading lean. Battling a pathfinder right now with both banks showing lean codes as well as a po430 code with it. So a 171 a 174 and a 430. Watching the live data. Bank 2 looks fine. Bank 1 long term is trying to add 37.5 percent and short term is trying to remove 25 percent. Also when cold starting it jumps straight to closed loop. When looking at the freeze frame from when the codes popped bank 1 fuel system says open loop fault and bank 2 is closed loop.

difficult to focus in on and concentrate with the background music going

Hi Salem! thanks for the video. My Subaru outback 2008 had the alternator changed and only after two drives, I got the check engine light on and the P0171 code I am being told that the PO171 code has nothing to do with any mistake that could have been done while working on the alternator replacement. I am being told the code is caused by a vacuum leak because the EGR valve is cracked. Is that possible? I have not heard any connection with the EGR Valve so far in any videos about this code. Thanks for your wisdom and expertise!

My 04 impala SS is sending the p0171. I’m also getting evap leak and o2 sensor codes. Could both of those be sending the lean code?

I got the PO170 and PO174 codes on my Nissan Murano. I noticed it was burning a bit to much gas and yesterday my wife said the car wanted to cut off on her. Taking it to PepBoys to get fixed tomorrow. I hope it’s not an expensive fix.

I got an 06' flex fuel Suburban and I got both of these codes immediately after filling my tank with E-85 . I erased the codes and they came back several times . I concluded the gas probably had water contamination . I ran the tank almost empty put in a bottle of fuel system cleaner and filled up with regular gas and the problem went away .!

Excelent. P0171. Checked fo vac leaks. Cleaned MAF. Air cleaner was dirty-blew off. Checked Blue Driver and numbers semed w/in range. Cleared. Drove. Outside Emissions I scanned. No codes. Went in:P0171. Why are they geting a code and I am not? Went home scanned with BD, NOW P0171 AND P0174. What happened?

Informative. But would appreciate if background music volume could be lower

I have this code on my chevy aveo the auto shop couldn't get it fixed due to being busy is this lean condition dangerous.

My car had no o2 sensors. It was running lean. I bought 2 of them from the junkyard and they worked for 3 days before the car started running lean again. I kind of smell has from the behind the car... I hope there's nothing wrong with my engine. Your feedback will be highly appreciated

I got an 02 Camaro ss, LS1 engine. I got this code after noticing that sometimes, especially when the engine isn’t warmed up, it will either stall when I go to neutral, or the rpms will rocket up to 2,000 at idle

Can it be the purge canister valve ? I change about everything. 😂😂😂

Buick 2000 3.8....my warning light problem began about 2 months ago. First it said gas cap loose, I cleaned it and that was solved...Then it became slightly difficult to start, so I would slightly tap the gas pedal and it would start right up. After a couple days it would start up normally again on the first turn of the key like it always has and still does now........a couple weeks ago the yellow check engine light came on and the code came up PO171. Then it when out by it self a couple days later, then came on again, and went out again...During all of this I have watched my mileage very closely, and my instant mileage for highway driving is 29 mpg, which I the same has it has always been, and the average overall mileage is 22, like it always has been......do you have any idea what the problem would most likely be? Also during this whole time the car has been idling and running very good......Thanks for any suggestions...............

Can cutting muffler cause this code on 2001 pt cruiser? I went to auto zone machine said map sensor I replaced it but still pop up

What about if I have system to lean in both bank, p0506 restrictions air, fuel trim short percentage are over 15 and 25% No vacuum leak, good fuel injector and pressure. Good compression in all cylinder, leak down test pass good. New O2 sensor I have the code p0456 small Evan leak, esim switch replace together the canister and the purge valve. No vacuum leak in the evap system. The purge valve sometimes work and sometimes won’t work, but sometimes work when put on the AC compressor anyone here had this same problem before and any solution? Os for a 2014 ram 1500 5.7l

solid! Excellent blend of info./flow...........the music could be several touches lower however

My 07 SC GP keeps telling me to check my gas cap I've got six of them they can't all be broken, sometimes it won't tell me, most of the time it will. I've noticed it' typically doesn't do it when the gas tank gets filled. I've checked vacuum leaks and all the sensors except for the one on top of the gas tank because dropping the gas tank is not something I look forward to doing, what is your suggestion. If it goes for a while it will throw a code saying large evaporation system leak. Also I have checked the canister and I've replaced that damn solenoid can't think Irv off the top of my head, but it's under the hood, behind the SC.

Where did you get that shirt

Can a broken box of air filter can cause a lean engine?

Ok I'm getting a lean bank 1 and bank 2 code in a 370z purchased that had intakes, I believe HFC, and cat back exhaust. No codes at test drive. Driving it 60 miles tripped the code. The engine seems to be running fine, smooth idle, no vacuum noises. Maybe it really is lean because of the mods? I'm thinking stock cats will fix this, but I have no idea. Have you encountered this with vehicles that had intakes, cats, and exhaust "upgraded?" Could the MAFs be dirty from a dusty road trip since it has CIA? I'm not going to try and fix it before Nissan hooking it up to their scanner. Sorry lots of questions but any input would help. I do not want to "get a tune." I'd rather put factory intake and cats back on before worrying about tuning. But the car came this way so I would be fine leaving the mods on if they can work.

So my sienna is running just fine but its sending 171 and 174...i was thinking 02 sensor...what do u think? Thanks

grand prix have the same code

I have bad luck with this code every time it ends up being intake gaskets

So 2011 Silverado went to mechanic for 100000 mile tune up. Came out of the shop, a day later check engine comes on - PO171,174 codes show up for the first time ever. Cleared them, they come back. What could the shop have done to cause this?

Code from hell. only on youtube fantasy life is always simple cracked hose or dirty or bad MAF sensor.

171. Lean 172. Rich please look and correct

Big explanation........but wrong. P0172 is bank 1 rich

Seeing this video makes me conclude you are a good K.I.S.S sir (Keep It Simple...STUPID)....what I'm trying to say is effing great video

THE MUSIC IN BACKGROUND IS SO LOUD...IT KEEPS. MY ATTENTION THERE. I JUST WANT TO CHANGE CHANNELS. VERY ANNOYING MUSIC..WISH THERE WAS AN OPTION TO LOWER MUSIC VOLUME OR JUST ELIMINATE IT. 😢

Man get to the point