Losing engine power with no warning

Hi Jim, thanks for your response. Apparently, this Yukon is suppose to go into the "low power mode" where it shuts off the a/c, drops you down to <30mph or so when the engine overheats! But it appears there is a miscommunication occurring = no check engine light, no protective mode etc.. The coolant temp sensor seems like a good place to start! To my limited knowledge, it didn't appear to be overheating (no bubbling, steaming, hot smell etc) and the gauge read pretty normal till the engine cut out! But I will check on the sensor, thanks!

My 07 Yukon denali shut down on me it seems like it's fighting for gas but I had gas in the tank is change the fuel pump but getting the same problem when I drive the truck regular I don't get that problem but when I drive it hard it start shaking and shut down and when the engine cool down it would start back can someone tell me what is that problem please

did you ever find the problem my 2002 has started doing the exact same thing

Hi all. So I was having the same issue where my 2012 GMC Yukon XL Denali would randomly go into limp mode with no rhyme or reason. Every time it did, we would bring it to the local Chevy dealer, but they were never able to find a problem with it. It had happened again one time & caused my wife to get into an accident. We immediately brought the car back to the dealership and once again, they couldn't find anything wrong with the vehicle. After the repairs were done from the accident, we got the vehicle back and low and behold, it happened again. Long story short, this time we brought it back to the dealer, and the service manager told me that when we get there, don't turn the truck off and come and get him. Well, this made a difference. Apparently, every time we brought the truck there, we would park it and turn it off (as reasonably expected) which would in turn reset the computer the next time it was started up. Since we never turned it off, he hooked up the code computer and was able to get 2 different codes from the vehicle. One of them showing that there was an issue with the transponder in the key which was screwing with the receiver in the ignition sporatically, and the vehicle would think that it was being stolen and go into limp mode. The service manager had a new key made up, and we haven't had an issue with the electrical system since. Hope this sheds some light and helps.

My 08 Yukon Denali is having the same problem. $800 in mechanical bills and it’s still doing the same thing. Shannon did you ever figure out what was causing??

I think I found the problem

2005 GMC yukon xl ... losing power too. When u first start it .. it's good. When you press down on the accelerator pedal it doesn't work... it just gets slower and slower. I really need help. Thanks 6.25.19

Try unplugging it from your gas pedal inside the truck and plug it back in

so i have owned an 04 denlai for about a year and half... this is my second winter owning it and i have been going into "limp Mode" again for about 2 weeks after not having done so all spring summer and fall... this led me to believe it had something to do ith the cold itself.. this am i accidently found the issue for my truck and hope it helps you.... so i have a code scanner and always come up with "throttle communication loss" as a code while in "limp mode" , usually i reset the codes wait a few mins and after a couple tries the computer will reset and TC indicator goes off as well as coming out of fail mode.. i started out checking sensors which all seem to work accordingly, then checked harnesses, ensured grounds were properly connected and tight , cleaned the throttle body, done everything i can think of under the sun and moon.... then something happened : last week i noticed my dome lights werent coming on anymore and just figured i blew a fuse, But THis am i was going through the code reset when suddenly my dome lights came on for just a moment ... it struck me funny cause i know the fuse blew (or so i thought) checked it and it was GOOD.... so then i go sit back inside truck which was running for the 3 min reset period..... and reach for the dome light switch... the switch is automatically in auto mode , i switch the light switch to full on and the RPMs Rev.. i immdeiatly switch it off since thats gonna mess up the 3 min training period its i. As i switched the lights to the full OFF position instead of auto, the RPMS dropped to the exact amount i would need to reset the computer... when i let go of switch and it went back to auto the RPMs raised yet again.... and then the light in my head came on... its not a ground issue with the engine or the harness for the throttle body itself or the pedal... its the damn light swtich or the light system itself.. SO .. i hold teh switch to off position and hold it there, recrank truck, reset codes, hold the switch off and wait 3 mins and BOOM.... truck comes out of Limp Mode..... its not just cold when the truck acts up ... its early am or late evening when the sun is gone and the AUTO LIGHTS are turned on... i now know for a fact that there is something wrong with the switch itself or in the lights harness... who would have ever figured..... GOOD JOB GM ENGINEERS for that fuckery