2003 GMC Envoy Logo
Anonymous Posted on Dec 14, 2009

I have a 03 gmc envoy. My reduced engine power keeps coming on. I had the paddel changed first did not go away, then the throttle body cleaned did not work ,Then I had the throttle body replaced still reduced power to about 20mph. also had plugs and sensers changed, where to look now.

  • 9 more comments 
  • Anonymous Dec 16, 2009

    I spelled a few things wrong! Forgive me! But I did have the pedal and the sensors changed. Also the throttle body with other wireing done.Now they are saying that it may be the ECM that has to be changed.I just put a lot of money in this truck and what if this is still not the problem. Should i change this part.

  • Anonymous Dec 17, 2009

    So if I block off the ERG valve and it dies or not dies what do this mean what do I fix.

  • Anonymous Dec 17, 2009

    I also wanted to say that what about my cat converter,or I also need a new thermorstat, my car is not heating up all the way. It's not over heating.

  • Anonymous Dec 18, 2009

    So do you think if i change my thermostat my reduced engine power would stop happening going 20mph!!

  • Anonymous Jan 15, 2010

    IT'S BEEN A WHILE BUT WHAT IS A ERG VALVE. AND WHERE IS IT LOCATED.I KNOW NOTHING ABOUT CARS.

  • Anonymous Jan 21, 2010

    anymore help out there!! need car fixed!!

  • Anonymous Jan 23, 2010

    THE MACHANICE SAY THIS YEAR 03 ENVOY DO NOT HAVE A EGR VALVE..

  • Anonymous Jan 25, 2010

    they say for this year and model car they stop making egr valves. i changed the thermostat anyway because i had a code come up for it to be changed. also on my dash the temperature gage would not reach the middle.now sence i changed it, it in the middle.should i still try what you said. or could it be my ECM. PLEASE NOT THAT.

  • Anonymous Jan 26, 2010

    O.K. my check engine light in nov. then a few days later my reduced engine light came on while driving to reduced to about 10mph had to turn car off,then turn it on drove fine to two minutes then it happened again. it still happens till this day.took it to a local manchanic put it on there machaine they said the code read to change peddle.I did same thing still happing.took it to the gm dealer put on their machine the code said throttdle body. the cleaned that,was not it then they replaced it,was not it then changed some wiring,was not it, now they want to change my ECM.I paid about $1,100 for all this stuff, still not working. and this other job the gm want's me to do is about $800.00.not labor.i cleared all the codes.as can you tell i am a girl that needs this help. should i take it to another dealer. and can i get my money back. and i change my thermostat.

  • Anonymous Feb 12, 2010

    CHANGED THE ECU THAT WAS NOT THE PROBLEM. NOW THEY ARE TRYING THE FAN CLUTCH. THEY ARE AT A GUESSING GAME. COULD THIS BE IT.

  • Anonymous Aug 23, 2010

    On Feb. 15, 2010 i took my car back to get my fan cluthc fixed. This was the problem all along. It kept reading low on their machine but they left that for last because the reading was so low.This was the problem!!!! my car has been running good ever since. It's teh fan clutch!!!!

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2 Answers

Colin Stickland

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  • GMC Master 22,516 Answers
  • Posted on Dec 14, 2009
Colin Stickland
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Sensors on the pedal?? not sure what you mean by paddel though never heard of this term before

Testimonial: "03 Envoy:My reduced engine power keeps happening. My car goes 20 mph. Changed throttle body, pedal, wiring. Need new thermostat. Car not heating up."

  • 5 more comments 
  • Colin Stickland
    Colin Stickland Dec 16, 2009

    hmm not sure about this ,but before you spend anymore hard earned cash ,try blocking off the ERG valve ,you know the one between the inlet and exhaust manifold .try that first and see if dies after that

  • Colin Stickland
    Colin Stickland Dec 17, 2009

    if engine runs ok then thats your problem,as for the cat if it was blocked it wouldnt run simple as that .thermostat ,yes it must run right temperature or engine will be running on autochoke which will cause the cat to fail .

  • Colin Stickland
    Colin Stickland Dec 19, 2009

    check the engine temperature is correct before you change the thermostat,look at the erg valve first ,this will cause engine to lose power and give the symptoms you describe

  • Colin Stickland
    Colin Stickland Jan 16, 2010

    got to go to work ,have a another look at this question tonight

  • Colin Stickland
    Colin Stickland Jan 24, 2010

    if engine is not reaching temperature then this can cause the cat to block up ,before you go any further try disconnecting the exhaust at the manifold ,i know it will sound like a tractor but try it ,if it runs ok you need a new cat

  • Colin Stickland
    Colin Stickland Jan 26, 2010

    you are changing sill things for nothing ,just because a gauge has the wrong resistance and its showing a bit different to teh norm is not an excuse to wast cash on it.please describe what the problem is now and what has been done to it so i can give a second opinion but i would have expected your local mechanic to have been able to tell you whats wrong with this vehicle straight away .Or your money back



  • Colin Stickland
    Colin Stickland Jan 28, 2010

    yes i would have gone for the computer ,so two choices either trade it in quick ,or try to find the complete works from a scrapyard ,like a ECU ,the key chip and the transponder ,so it will run straight away,the dealer will not fit a secondhand one they want the profit

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  • Posted on Aug 16, 2010
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I don't think I have a solution, however i believe to have information which may help. The same thing happened to my 2003 envoy XL. each time i brought it to the dealer, they found no codes at fault. I almost thought they didn't believe me. I would drive for a few days and it would happen again. i do lots of highway driving so i'm getting good at the re-start thing. One day, it happened only a few miles from the dealer. I decided to drive there (20mph) with flashers on. i pulled in and got my guy and made him drive the truck. he plugged in his computer gizmo and said he has a few codes to review. The truck is there now...we shall see...

  • Anonymous Sep 19, 2010

    the dealer fixed it. actually it was part of an original problem from 3 years back when some squirrels got in and chewed on a wire harness. some of the repairs came apart and were shorting causing "reduced engine power".

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3 Related Answers

Steven Gepner

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  • Posted on Jul 08, 2010

SOURCE: What does reduced engine power light mean

this model has what they call fly by wire.. no accelerator cable. If the computer detects a problem in the thottle system it will not allow the engine to accelerate and will show reduced power and possibly set a check engine light. The dealer usually wants to replace the throttle assembly which is very expensive and usually un nessesary.
I have had a lot of succes with just cleaning the throttle plates real good.

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NumbNuckles

  • 40 Answers
  • Posted on Feb 23, 2010

SOURCE: 2002 gmc envoy check engine and reduce engine

typical causes: dirty air filter, clogged up catalytic converter

Anonymous

  • 462 Answers
  • Posted on Oct 10, 2009

SOURCE: 2004 GMC 2500, 6lt. V8. Reduced Engine Power Keeps

Have the codes checked first and go from there.

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I have a 2004 gmc envoy. I have replaced the throttle body and all sparks plug or core packs . Now I have a reduce power engine Light that comes on when it wants to when it comes on you have no power

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I have a 2002 gmc envoy with 4.2 i 6 with 65k the reduce engine power light came on, and it would only go about 10 mph. After it sat a day or so it ran go for about a week then it did it again.now the...

Sounds like your throttle body is sticking. Common problem, the reduced power is just a safe mode. 1st disconnect your battery, then clean your throttle body with throttle body cleaner. When finished, connect the battery back up. Turn off all accessoried and drive around for 20 minutes or so, for the computer to relearn a properly functioning throttle body. Should solve your problem, and if you do it yourself, will cost you around $5 for the can of TB cleaner.
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Reduced engine power is just like a safe mode. First things first, clean your throttle body. It's possible the butterfly is sticking. Disconnect the battery, clean your throttle body with throttle body cleaner, must be nice and shiny. When finished, drive around for 20 minutes or so with all accessories off. This will allow the computer to relearn a properly functioning throttle body.
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I have a 2004 GMC Envoy, while I,m driving the reduce engine power light comes on then it dies! This happens 10 to 12 times a day. It will sometimes do it if I change the heat from high to low or the...

Clean your throttle body for starters. When this is filthy, and it will be filthy, the throttle body will learn some bad habits. So the engine will go into a safe mode "reduced power". Clean the TB with TB cleaner with the battery disconnected, must be nice and shiny front and back. When finished, connect the battery back up and drive around for 20 minutes or so with all accessories off. This way the computer will re-learn a newly cleaned, properly functioning throtte body. This seams to be the main culprit with this problem. Hope this helps!
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The reduced engine power light has been coming on in my 2003 Envoy

1st things first, clean your throttle body with throttle body cleaner. Clean it with the battery disconnected. When finished, drive around for 5 or so miles to reset the computer. The butterfly in throttle body is probably sticking. The throttle body must be nice and shiny when finished.
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REDUCED ENGINE POWER IN A 03 ENVOY

may have a bad throttle body check for codes if you have a p01516 must of the time it is a throttle body problem
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