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97 K3500 172 175 codes ??

Discussion in 'Chevy Trucks' started by scottL, Jun 26, 2005.

  1. scottL

    scottL PlowSite.com Addict
    Messages: 1,613

    Yesterday I helped out doing SAG support for an all day cycling event. The air temp was 97 and I had my truck running mostly from 6:am - 8pm. During the day I noticed the Service Engine Soon light come on. Somewhat on/off throughout the day but, mostly on.

    Today I just did a short run and the light did not come on. Air temp is 93 degrees. I went to AutoZone to have them read the codes and it came up with 172 & 175 ( they claimed too rich of a fuel mixture ).

    Truck seems to idel and run just fine. Maybe a very slight hesitation but, probably not noticeable to anyone else but me. About 5 days ago I had the cooling system flushed by the Chevy dealer.

    Any idea what the codes are actually? The obvious follow on is how/what to correct?

    K3500, 1997, 5.8L, 4x4.


  2. calhoun

    calhoun Senior Member
    Messages: 165

    These are engine too rich bank 1 and bank 2. This can be caused by a leaking pressure regulator or dirty injectors. (If codes were set at idle or low speed I would suspect the regulator.)
    Hook up a pressure guage to the fuel rail. Turn on the key (no start) notice the pressure reading. Turn off the key and check the reading after 10 min. If it has droped more than 20lbs your regulator is leaking.
    If the injectors are dirty the spray pattern isn't correct so fuel doesn't burn as it should. O2 sensors than pick up excess fuel and set the code.
    I had the same codes on my 97 3500. Had dealer do an injector cleaning and that fixed it.
  3. scottL

    scottL PlowSite.com Addict
    Messages: 1,613

    I had gone the course of the MAF first. I bought an aftermarket unit from Garnallie (sp?) sports. It was $150 cheaper in cost than the stock unit from Chevy and boasted some marked improvments. So far, all is better. In fact the truck now feels like it has some new life.

    My next choice would be the regulator.......