2002 Yukon - Service Light - Mass Air Flow

heatheriheatheri Member Posts: 1
edited July 2014 in GMC
I bought my 02 Yukon new and have never had any problems with it until recently when the service engine light came on about a week after I got gas at a local convience store. I took it to Auto Zone to run the codes and it kept showing "lean". So, the guy thought maybe I got some gas w/ water in it or something. So, he cleared the code and I went on my way. A couple of weeks later, it came back on. I went back and they ran it again. It showed the same codes, so I bought some octane booster and put high end gas in it. They guy that cleared the code this time said it might be a mass air flow problem. That was Sun. Today the light came on again. Any clues as to what it might be? I was thinking of letting this tank of gas run through and then clearing the code and filling up again and pray that's all it is. I doubt I can be that lucky. My MPG have avg. around 11 for awhile now. Is that a good gas mileage for this year and make? Thanks!


  • rshtrsht Member Posts: 277
    What was the code shown on the scanner? PXXXX...
    If indeed its the "Mess Air Flow Sensor", you may want to first visually exam the sensor for any dirt/dust build-up on it. If it needs cleaning, make sure you remove the sensor from the hose "very carefully and not to drop it"... I have used QD Electronic Cleaner on mine before, just spray clean the sensor without touching or getting too close to the sensor. Make sure to let it air dry before reinstall and clear the code... DO NOT use Gumout or Carburetor cleaners as they are too strong and will leave residue on the sensor. Only use spray type "Electronic" device/contact Cleaner. Hope that will help.

    BTW, is the air filter in good shape...? Just checking the basics...
  • rshtrsht Member Posts: 277
    BTW, CRC also makes the specific cleaner for the Mass Air Flow Sensors. You can find it in your local auto parts stores.
  • mrsshagstermrsshagster Member Posts: 2
    I have a 1999 gmc Yukon slt and my engine light has been on for about a year already. I dont know what the problem is but I went through 2 gas pumps already. The motor was replaced for one on a 1997 tahoe cause the original motor needed some work. Now my problem is the torques holding the starter, they keep breaking and stalling me every other month. Please help me. :confuse:
  • mrsshagstermrsshagster Member Posts: 2
    Ok, I think I know why my torques on my starter keep breaking. What I need advice on is, my ignition switch. When I try to start my truck in the morning or all through the day, it does'nt start on the first try all the time. Sometimes I have to put it on Neutral or open the ignition switch 4 times before I try to crank it. When I do crank it, it makes a grinding noise or as if the starter had slipped and was just turning fast with no cranking. You think it might be the ignition switch? :confuse:
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