Rough Idle, Check Engine Light

Discussion in 'General Chevy & GM Tech Questions' started by npete7381, Feb 11, 2012.

  1. npete7381

    npete7381 New Member

    I have a 2005 Silverado 1500 with the 5.3L engine with 62,000 miles. I had just left home yesterday and came to a stop at a stop light when I noticed the engine was idling rough. It was enough to make the tach fluctuate a little and I could feel it in the cab. As soon as I accelerated the roughness went away and everything seemed to be fine. When I came up to the next light the rough idle came back. At the third stop light in addition to the rough idle I could smell a strong sulfur catalytic converter smell and the check engine light started flashing. Once I was moving again the smell and roughness went away, but the light stayed on. Anyone had a similar experience? Any suggestions?
  2. Red Z71 Max

    Red Z71 Max Rockstar 4 Years ROTM Winner 1000 Posts

    Sounds like an O2 sensor or possibly the Catalytic Converter is starting to plug.

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    If you go to your Local Auto parts Outlet, Auto Zone, O'Reillys etc, they will at no charge, Scan your Trucks Computer, and will be able to pull the Trouble Code that is causing the Check Engine Light to come on, at that point you'll be able to know for sure what the Problem and/or Issue is.....From what you have expresses, the Problem as mentioned above......may be with the Catalytic Converter.
    Last edited: Feb 11, 2012
  4. npete7381

    npete7381 New Member

    Looks like it's an O2 sensor, which is what I was thinking/hoping (vs. a problem with the cat) Stopped by my local Advanced Auto today and used their scanner and got the following codes:
    P0131 - Left bank upstream sensor, low circuit voltage
    P0171 - Left bank upstream sensor, lean mixture
    P0300 - Random engine misfire

    Of course I had to order the sensor, so it'll be a day or two before I get it fixed but at least it's not something more serious. Thanks for your replies!

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