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egr problem

Discussion in 'Chevy Trucks' started by monson770, Dec 1, 2014.

  1. monson770

    monson770 Senior Member
    Messages: 133

    so, i have been dealing with a p0404 code, and also a p0405.. 2002 gmc sierra 2500hd
    i have replaced the egr valve, the connector, and the egr tube has been replaced within the past year or two.. this seemed to have been fixed for a short amount of time, but the light continues to come back.. it had been off for several months earlier in the spring/summer months. just to return this fall.. it stayed off for only about a week or two when i just bought a new egr/connector a few weeks ago...
    what i am looking for is anyone with experience with this issue. not someone who just has read up on it online. i have already done this.
    from what i can tell, it is either another faulty egr, or there is a problem with the pcm, or there is a short in the wiring somewhere.. i know that faulty parts are a possibility, but id like to know if there is anyone that has dealt with this exact issue..

    also if anyone has replaced their pcm and/or had it maybe re-flashed/reprogrammed and had it fixed

    any useful help is much appreciated.
    Last edited: Dec 1, 2014
  2. leolkfrm

    leolkfrm PlowSite.com Addict
    Messages: 1,980

    diesel or gas?
  3. crete5245

    crete5245 Member
    Messages: 61

    This truck uses the Mass Air Flow sensor to detect if the egr valve has opened. If the MAF does not show a change in flow when the egr valve is commanded on then the pcm will throw a egr code when actually it is the MAF sensor is bad or slow showing the change.. try to get a good scan tool on it and clear codes and drive it till the light comes on then go into freeze frame and look at the history an look at the MAF and see if it changed when the egr came on.... A tec 2 would be the best scan tool for this truck as it is the factory tool....
  4. monson770

    monson770 Senior Member
    Messages: 133

    So I have replaced the egr valve on warranty and cleaned the MAF. Light is off and I'm hoping for the best. Unfortunately I do not have a tech 2, or the money to spend on one.. but thanx for the reply. I started noticing some shuddering on light throttle from a stop, and I know that the MAF was to blame the last time that happened. So I thought I'd just try cleaning it and hoping I got a faulty part.. we will see.