How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask GM expert tech Your Own Question

GM expert tech
GM expert tech, ASE Certified Technician
Category: GM
Satisfied Customers: 152
Experience:  20+ yrs. experience, ASE Master Tech, GM STC trained
10113660
Type Your GM Question Here...
GM expert tech is online now
A new question is answered every 9 seconds

what does lean bank 1 and lean bank 2 mean

Customer Question

what does lean bank 1 and lean bank 2 mean
Submitted: 5 years ago.
Category: GM
Expert:  Carhelp4u replied 5 years ago.
This means that both the right and left banks of the engine have been found to be running with an improper fuel air ratio. In this case you have more oxygen than you should causing for a lean condition. This problem can be caused by low fuel pressure, exhaust leaks, faulty injection components, or even vacuum leaks to the engine. Feel free to contact me with any questions or problems! Good luck!
Customer: replied 5 years ago.
i have checked for leaks and cant seem to find any can this also be caused by a bad o2 sensor and if so how do i know wich one i heard that there is 4 o2 sensors on my 1999 gmc yukon
Expert:  Carhelp4u replied 5 years ago.

I would not see a faulty oxygen sensor causing for a lean code on both banks. I really would recommend that you do a fuel pressure test to verify that this truck is getting 60-66 psi of fuel pressure.

Customer: replied 5 years ago.
i dont know if this can help but when i put my truck on the computer it gave me this code po171b bank 1 system too lean and po174b bank 2 system too lean
Expert:  GM expert tech replied 5 years ago.

Hi, I'm James. I have seen two problems that generally set these codes.

 

First, the Mass Air Flow sensor becomes contaminated and reports a lower air flow to PCM than actual, so PCM does not command enough fuel. You either need to clean MAF sensor or replace it.

 

Second, the intake manifold gaskets leak air so that the MAF sensor data again is too low causing a lean condition. GM has developed a new gasket to repair this problem.

GM expert tech, ASE Certified Technician
Category: GM
Satisfied Customers: 152
Experience: 20+ yrs. experience, ASE Master Tech, GM STC trained
GM expert tech and 3 other GM Specialists are ready to help you
Customer: replied 5 years ago.
Thanks james you were a great help.. i changed the mass airflow sensor and it seems to have fixed the problem... if i have any more questions i'll be sure to ask for your help as i'm in the process of trying to pass my emissions test..thanks again..
Expert:  GM expert tech replied 5 years ago.
You're welcome.

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Gary

    GMC Technician

    Satisfied Customers:

    903
    15 years gm master tech/15 years ASE master tech
< Last | Next >
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    GMC Technician

    Satisfied Customers:

    903
    15 years gm master tech/15 years ASE master tech
  • http://ww2.justanswer.com/uploads/CA/caprio23/2011-12-13_155550_20111213105344.64x64.jpg Anthony's Avatar

    Anthony

    ASE Certified Technician

    Satisfied Customers:

    476
    ASE Master Automobile Technician with over 20 years exp.
  • http://ww2.justanswer.com/uploads/Rocket2005/2009-09-13_133703_jack.jpg car tech's Avatar

    car tech

    ASE Certified Technician

    Satisfied Customers:

    448
    25 year master tech and shop owner
  • http://ww2.justanswer.com/uploads/2P/2paulm/2012-4-4_183431_justabswer.64x64.jpg Paul M ASE Master's Avatar

    Paul M ASE Master

    ASE Master Tech

    Satisfied Customers:

    187
    ASE Master Tech 20+ Years
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka- Moose)'s Avatar

    Chris (aka- Moose)

    GMC Technician

    Satisfied Customers:

    89
    16 years of experience
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    GMC Technician

    Satisfied Customers:

    360
    ASE Master Technician advanced level specialist
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    GMC Technician

    Satisfied Customers:

    2262
    ASE Master Certification. GM World Class Certification