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Username Post: "Reduced Engine Power" '04 Silverado        (Topic#285233)
Forum Newbie
Posts: 14

Age: 25
Reg: 04-09-12
08-07-12 04:46 AM - Post#2256686    

I was low on gas the other day, but not the lowest I have ever been, when I got the message on my dash "Reduced Engine Power."

The max speed I could reach was maybe 15mph. When I pulled over I felt the truck shaking like it was seizuring. When I looked up the problem some people said it was an acceleration sensor problem. Getting my a diagnostic is expensive in my area so I am wondering what tips/advice people here have.

The last time I had a problem every person I actually met with was wrong in telling me how to fix my truck. Even the dealership!

Asking the same questions here yielded the correct answer!

I also have a "tighten fuel cap message" that comes up, even after I replaced it and my entire dash cluster is screwed up just like one of the other topics here describes if that affects my main question.

I drive a 2004 Chevy Silverado 2500HD crew cab non-diesel for reference.



LMC Trucks
Bad Bowtie 
Valued Contributor
Posts: 4707
Bad Bowtie
Age: 43
Loc: TX
Reg: 07-04-03
08-07-12 08:34 AM - Post#2256756    
    In response to HermSC

I sthere an Autozone in your area??? They can at least scan your truck for free, then you can post the trouble codes on here for us to give some form of opinion. Sounds like multiple problems though to me...

If you already replaced your gas cap with a new AC Delco/GM one, I bet you have a vacuum leak at the tank- Possibly the dreaded fuel tank pressure sensor...

GMC. We are Professional Grade.

Forum Newbie
Posts: 14

Age: 25
Reg: 04-09-12
08-07-12 11:59 AM - Post#2256808    
    In response to Bad Bowtie

I went to Autozone and they could not even connect to my trucks computer to get the trouble codes. We checked the fuses and they were fine too.

Any ideas?

Forum Newbie
Posts: 14

Age: 25
Reg: 04-09-12
08-09-12 04:29 PM - Post#2257688    
    In response to HermSC

I got my multimeter out and fixed some wiring then got the trouble codes.

The are:

P0455 (2 of these)

Posts: 674
Age: 56
Loc: Western, N. Carolina
Reg: 02-01-05
08-10-12 03:12 AM - Post#2257780    
    In response to HermSC

The first one is an electrical issue with the evap solenoid, Could be related to the wiring repair you made.

Second is the gas cap loose or bad code.

The third is throttle body related and I have a link that explains it. che...

1959 El Camino
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2004 Z71
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Forum Newbie
Posts: 14

Age: 25
Reg: 04-09-12
08-13-12 05:21 PM - Post#2258966    
    In response to DEI8FAN

The wiring that I fixed was for my cigarette lighter that I cut a while ago to try to install an extra light.(This was back in high school ) That was apparently the reason my computer was unable to be read by the scanner.

I removed the EVAP solenoid and took some compressed air to it (It was pretty dirty) because that was a solution I read on another forum. But am trying to figure out the wiring problem that you describe. (I was watching some of this: )

As for the gas cap code, I replaced the gas cap a few months ago and the problem continued. I read elsewhere that the code could also be a large leak code. I'm thinking of doing a smoke test on it but am unsure where to feed the smoke in to.

And finally for the TAC code, I looked at my TAC and the wiring going into the throttle body. There is one wire(light blue) by the throttle body that concerns me because it felt a little loose and was able to be bent pretty easily compared to the other wires, but I am not confident that I should cut the wire to see.

What are some things that I can do about these issues?

Should I get the codes cleared and see if they return?

LMC Trucks
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