P0171 Trouble Code: System Too Lean Bank 1 Diagnosis

In this video, I show you how I troubleshoot a Check Engine Light (CEL) / Diagnostic Trouble Code (DTC) P0171, System Too Lean Bank 1. The exact vehicle in video is a 2002 Toyota Tacoma standard cab 4 cylinder pickup truck. The techniques shown can be used on many vehicles, not just Toyotas.
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The Big Dog50001 Automotive Channel recommends safe practices when working with power tools, in on or around automobiles or other vehicles, automotive lifts, lifting tools, jack stands, electrical equipment, automotive modules and systems, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video.
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[@evandrewmartinez1]

This video made me feel like I already fixed my po171 and I haven't even went outside yet

[@tonyfox1434]

I watch and learn diagnostic trouble codes daily and to be honest, your way of using a cheap code reader with live data was the most interesting and informative video I have seen in a long time. Thank you, and all on a cheap device !!

[@m2svirtual384]

It would be impossible to add up all the hours of auto repair videos I've watched over the last 8-10 years. THIS ONE, though, MAN!! In only 46 mins... I'm speechless at how easily I absorbed every concept and it made logical sense. I was starting to diagnose ahead of you! You sir, not only have a gift of mechanics and troubleshooting, you have an even greater gift of TEACHER. Never boring, just a concise step-by-step stream of logical information. I stood at a standing ovation at the end of this video, and I cannot thank you enough for the education you imparted upon me. Thanks Dawg!

[@SDMev1982]

Some of the best 46 minutes I’ve ever spent.

[@cal48koho]

hard to overstate how sharp this guy is. Beautiful explanation . This is at a high level expert mechanic level!

[@stupagia26]

i don't normally respond to videos, but I almost felt like this gentleman was standing next to me and showing me all this in person and not shouting at me. Best of all is I appreciated how he explained everything he was looking at and what significance it had in terms I could easily follow along with. Turns out he lives in my neck o' the woods. Thanks Big Dog! I promise I won't tell, Scotty! :{>

[@billlincoln6087]

THE BEST MAF DIAGNOSTICS ON THE INTERNET.

[@robertlardon3782]

The most thorough and insightful "how-to diagnostic" car video I've seen! The 46 mins went fast with no fluff; just great information. Big Dog is a great mechanic and teacher!

[@user-sq8rs2lc9c]

THE MOST DETAIL DIAGNOSTICS PROCEDURE PRESENTED IN THIS CASE STUDY. SO BENIFICAL AND ACCURATE. THROUGH DIAGNOSTICS

[@michaelclayton4703]

As a driveability expert myself, you did an absolute awesome job, for not only a layman, but also experienced technicians! I am not ashamed to say I picked up a few tips too! Outstanding!

[@ashercohen4739]

First of all, thanks for the video, I'm trying to understand the fuel and air problem, it's not easy, but now I've learned something else, it's 85% of vehicle problems, thanks again

[@joelbarndt6907]

Great vid! You just saved me from taking my car to the repair shop. Read the code and had a closer look at the hoses. Plain as day one hose had come loose. Thank you!

[@netwonc]

The very best analysis of this problem. Shows how to test all systems. Thanks for sharing your knowledge with us.

[@spiketaterman5181]

Thanks for this! Was driving my car over rough roads, and the check engine light came on. It threw a P0171 code. Once home, I popped the hood and saw this plastic chamber thing had fallen off the air intake throat pipe DOWNSTREAM from the MAF sensor. Popped it back on and tightened clamp with a screwdriver and good to go! I love youtube university...

[@ericjernigan655]

Hands down the best diagnostic video I've ever watched on KZbin (and I've watched a ton). I learned more in that 46 minute video than all the others combined. Outstanding teaching video.

[@retiredsoon1365]

Had a similar problem on my old Toyota Yaris. using an a very basic analyser fault codes only. I followed your advise and found a damaged air line going to the throat of the Mass airflow. Replaced with a generic hose now idle is restored and my old car lives to fight another day. Thank you for your video.

[@erobbinstube]

I came here trying to track down a P0171 code on a 2003 Toyota Corolla, and while I think my problem is due to a leak at the intake manifold, I was floored by the quality of this video. I work in the high tech field and work on troubleshooting issues on a daily basis. This video is a text book example of the method needed to properly come to understand the root issue of a problem. Outstanding video.

[@rubbermalet9292]

this is actually "prime time info" bro

[@stealthg35infiniti94]

Thank you very much for helping fix my car. First it started with a P0420 Catalytic efficiency code. Then graduated to a P0171 lean code. Your method of explaining Fuel Trims issues and MAF Sensor testing was the Key to determining a vacuum leak. Then I looked at all hoses and used Brake Cleaner still couldn't find the leak. Finally after a quick prayer, I remembered, don't forget the brake Booster and PVC valve. Sure enough, I pinched the PVC hose to the intake manifold and the short trim fuel went from Maximum to Zero in bank 2. Bank 1 went from Maximum to about 3. Tomorrow I'm installing a new PVC valve.

[@quintingooing5495]

This video was the single best KZbin tutorial I’ve ever seen