2005 Tahoe Z71 5.3L with 125,356 miles. Recently changed oil/filter, air filter and ran 2 ounces of Lucas fuel system cleaner through it. Check engine light came on yesterday. Is there a component of the emissions system that is ready to be replaced and causing this warning? I first checked the gas cap, and it was tight!

 

Go to Autozone and they will check the code for you for free. There are also other stores that will check for free. Why guess when you can get the correct answer.

 

bgsick Welcome to the forum...

oldchevy offers good advice.., find out what the codes are and go from there... write them all down and have them cleared.
Also check your under hood work, its possible you left the MAF connector loose when you changed the air filter or knocked something loose while doing your servicing...

 

Thanks for the tip! I checked all my work, and found nothing out of place. I went to Auto Zone, and the manager told me that they are not allowed to perform this diagnostic test per California law? I could not find this law, and didn't get a warm fuzzy from the guy to begin with. I disconnected the battery to see if the light would go out, and after 45 minutes, the light came on and stayed on when I started the engine.. It idles smooth, and runs great on the road.

 

not sure why he couldn't check to see what codes were set, as that could have been an opening for them to sell you parts...

Well any stale codes were cleared out when you disconnected the battery, so what the light is on for now should help point you in the right direction...
Do check to make sure your gas cap is on correctly and the seal is clean...
its possible the fuel additive could be messing with the engine. trying another fill up from a different station may also help.... NOW I make these suggestions not knowing what code(s) you may have set. They are just good general things to consider before pouring money into shot gunning parts...

 

So, I go to the local Pep Boys store because they offer the free code reader service. The code pops up as PO332 which translates to faulty knock sensors. The guy then offers replacement service with an estimated price of $1200 - $1400. I find the parts on line for under $50, and since I am experienced with auto repair, I make the repair in under three hours. I think I need to get back into the business! Would have been the easiest grand I could make!!

 

I realize they need to make some profit, but $1200-$1400 for $50 worth of parts and 3 hours of labor? What crooks! Glad you were able to save a load of cash. Feel sorry for the ones that fall for that.