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1998 GMC C3500 truck loads up under a load

Tiny
ALLPARTSRACING
  • MEMBER
  • 1998 GMC C3500
  • V8
  • 2WD
  • AUTOMATIC
  • 90,000 MILES
My 1998 cheyv 3500 flat bed will die out under load and start back firing, it was running good until one day on the hight way the front 02 sensors just started reading 000 and the truc would not idle up and it feels like its in limp mode now, I keep getting codes saying low voltage to the front 02 sensors and once I clear the code it will drive ok for about a mile or so and then it just starts running real bad again.
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Sunday, November 16th, 2008 AT 3:17 PM

3 Replies

Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
When you clear the O2 sensor code(s), do the same codes keep coning back? An O2 sensor is like a battery that sends a voltage signal to the ECM in 10ths of a volt. If your sensor is reading 000, as you say, there is no signal to the ECM so, it has to guess which puts it in "limp" mode. You can test the O2 sensor by removing it and with a voltmeter attached, heat the sensor tip with a propane torch and watching for voltage rise. Warning, if you put the same sensor back in, be sure to coat the threads with an anti-sieze compound or you'll never get it out again. Hope this helps and thank you for your donation, Jim.
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Sunday, November 16th, 2008 AT 3:42 PM
Tiny
ALLPARTSRACING
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  • 2 POSTS
Well I all ready replaced the 02 sensors and yes the same code keeps coming up.
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Sunday, November 16th, 2008 AT 4:08 PM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
Correct me if I'm wrong, but are the new sensors reading 000? Apparently, you are using a scan tool of some sort to get your readings?
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Sunday, November 16th, 2008 AT 5:10 PM

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