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Gas mileage change/no "get up"

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I have a 2015 Silverado 2500hd gas, 6.0

My truck has 30,000 miles. I have always gotten 16-18 mpg on the highway (70mph). The last week, I can't get above 9mpg on the highway (70mph), even going downhill. Also, may be my imagination, it seems that I have lost some power. The truck feels like I am pulling a trailer or have a heavy load in the back. Any ideas?

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The first thing that comes to mind and doesn't cost much would be a new air filter. I could be wrong though, but just a thought.

Also add, is all the normal maintenance up to date. Fuel filter, plugs. See if any codes have been thrown. And last, maybe bad gas? Did this start just after a fill up?




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  • 2 weeks later...

I have a 2015 Silverado 2500hd gas, 6.0

My truck has 30,000 miles. I have always gotten 16-18 mpg on the highway (70mph). The last week, I can't get above 9mpg on the highway (70mph), even going downhill. Also, may be my imagination, it seems that I have lost some power. The truck feels like I am pulling a trailer or have a heavy load in the back. Any ideas?

Hi j-mo,


We see that you are seeking the input of other forum members, and would like to offer our assistance as well. If you would like to discuss your situation a little more in depth, please know that we are only a private message away. Our team would be more than happy to assist any way that we can.


Thank you,


Bret B.

GM Customer Care

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There is a fuel filter in the gas tank. It's part of the fuel sending unit. I doubt it would be the air filter. You'd be setting MAF sensor codes by the time a filter became plugged enough to cause issues with engine performance.

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Sounds like you got a bad tank of fuel. Run it down and then fill up with some good fresh fuel from a top tier station (if you don't already fill up there. Even they can get a bad delivery of fuel from the terminal, or something washes down into the underground tanks at the gas station) and maybe add a can of BG44k to it as well, I really like the stuff. I use it twice a year. Not only does my repair facility use it, but so does my dealer service department, made me smile when I saw a service advisor recommending it as well as a professional fuel system cleaning to a customer who had brought her 15 year old Saturn in for performance issues.


Edited by Colossus
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  • 3 months later...

Was this problem ever fixed? I've got the same issue. I've seen a few other people do too and no one has posted if they got it fixed. I'm gonna go to the dealer and have a backpressure test done. Don't know what else to do.

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