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GMC Yukon Reduced Engine Power message



  • jhoov07jhoov07 Posts: 13
    Well, just got my 07 Yukon back from the service dept. For those not following, my check engine light came on. It was in the shop for approximately 2 hours. The tech received scan codes P04742, and P0455. Not sure what the first code is but the 455 code has to do with the evap system. They replaced the purge valve and reset the codes... We'll see how it goes...

    Customer service was great as usual. I just don't understand how the replacement part is $44, and the labor was $150...I wish i had some mechanical skills so i cud save myself a little bit of money.... oh well.... i feel your pain guys, but i cant give up yet even if i wanted too...i still owe too much on mine...
  • gmcustsvcgmcustsvc Posts: 4,251
    Thank you for the update on your concerns. I understand your thoughts about the cost, but at lease there is a warranty on their parts and labor. Keep us updated on your situation.
    GM Customer Service
  • Just under a month ago I purchased an 06 with 52k miles and spent ALOT of money for it. Broke down the day I bought it and had to have it sent back to the dealer in white water wis. They had it for a week and put over 200 miles on it and it acted up 1 time for the service manager but since he didn't have a computer in the truck he didn't get the codes. They ended up giving me a new battery and said we think that was it. I drove it for a week and this monday night I was in Milwaukee for a bucks game and it died on me. Got it started back up and made it to a parking spot. Went in a watched the game and thought it would be fine, I was wrong!!!! Left me on a side street in a not so good area until 2am!!!!!!!! Called dealer back yesterday and they came down to IL where I am and picked it up and left me a 1998 buick (pos). Just very upset with the whole thing! They should be changing parts not just telling me we drove it today 75 miles and nothing happened! Am just to the point of giving the car back and saying it's a lemon or asking to take it to another dealer! It isn't the only 1 with this issues so don't act like you have no idea what the problem is!!!!! We'll see if they even call with an update cause they never did the 1st time they had it. I always called them. What kind of customer service is that????? 1st GMC and nothing but problems. If anyone can help if you've had this problem please let me know..............Thank you soooo much Love my denali but is it a :lemon:
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964

    I'm sorry to hear you're having these difficulties with your new '06, and can tell you're frustrated with the experience. If we can be of assistance in working with your dealership, please send us an email to (include your name/Edmunds username, phone and address, the last 8 digits of your VIN and current mileage, and the name of your dealership).

    All the best,
    GM Customer Service
  • avanti274avanti274 Posts: 2
    edited April 2012
    It's been over a year since my 2004 Denali first went into the "Reduced Engine Power - Stability System Disabled" mode. Since that time I have replaced the TPS, the throttle body, the TAC module, a Yaw sensor, had the grounds and wiring harness checked, cleaned and lubricated all the associated wiring connections, and even replaced the intake manifold gaskets in trying to get it fixed. These attempted repairs, most of which were done at our local GMC dealership, have been very expensive and it's still just as broken as it ever was. It has kicked into "limp mode" more than once on the Interstate, in our driveway, and everywhere in between. Getting it off the road, shutting it off, waiting about 30 seconds and restarting it will get it running again with the check engine light on.

    There are two things it is now consistently doing. It runs rough (hesitation) when you first pull it out on to the road for the first couple miles until it warms up - then it seems to smooth out. If it doesn't smooth out or if it starts acting like it is going to go into "limp mode," I can engage the cruise control and it takes care of the problem. The cruise control does "jerk" the throttle on a long down hill run though. Does anyone on the forum have any ideas as to what the problem might be? Our dealership can't figure it out.

    I bought it new. It had 5 miles on it when I drove it for the first time. It has been a great vehicle until this problem crept up. It still looks great, when it runs it still runs like new and drives as good as it did when it was new, but it has become totally undependable. It just makes me sick....
  • If you look back in this thread, the original posts started Aug 22, 2006. That's is almost 6 years ago and we have seen nothing from GMC on this, except go to the dealer.

    The only fix that I have found that works, for now, is adding Seafoam dewetting agent, find it at any auto parts store. This means that there is nothing wrong with the intake portion of the engine. There is something wrong on the exhaust portion. Ia m guessing an O2 sensor or fuel filter, just ordered them and hope to repost for an update on what happened.

    I will not buy a GMC again. Not due to this problem, due to the lack of commitment from GMC to support the people that have bought their vehicles. I just want a safe car for my family to drive in.
  • nowwhat2nowwhat2 Posts: 9
    Look at my post! It's all about the wire harness!!! I agree GM sucks at customer service and backing up their products. And they wonder why they went broke. I just love how GM customer service monitors this site ( It really is joke). But always gives the the same text book reading to everyone. I haven't heard or worked with one GM customer rep. that has taken care of me. From what I see on here there isn't much action either.
  • Yes I have a case open with you and I spent an hour on the phone with Parker who is a JOKE for customer service and I'll soon be dealing with someone above him cause he should not have this job! I just spent way too much money for a problem like I'm having with GMC and GM customer service. I have both of them calling me a liar cause they can't seem to make it happen and just today it acted up for me with my two kids in the car so I filmed it on my phone so lets see what they say about that tomorrow!!!! Might just have to give the BBB a call on this one as well as my state legislator to see about the lemon law cause there is no way I'm gonna pay for this PROBLEM the next 6 yrs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :lemon: :lemon: :lemon: :lemon: So sick of this, I've owned the car for a month and the dealer has had if over half the time and not been able to fix anything! & now the dealer tells me I need to wait until monday to bring it in, no loaner when I'm an hour and a half away & I need to take a day off of work to see them. How is this customer service. Dealer flat out told me, it's a used car we didn't need to do anything for you!!!!!!!!!!!!!!!!!!!!!!!!!! I have so many of those types of things from the dealer so when it's time to do something if they don't fix it I have them all written down and who said them. Hope to hear from you sarah! I'll give you my case # if you need it. Hope to hear from you tomorrow. Thanks, Brian
  • So over the past 6 years I have had my vehicle it has shut off in the middle of driving over 10 times. 9 of the 10 times my family and I were on the highway out of town; I have taken the vehicle to various dealerships and they all say the same thing "the computer reading is not coming up with any codes." I contacted the GMC Corporate office and they state they have never heard of this happening with any of there vehicles. Normally the vehicle will start back up once we cut off the radio and open and close the door; except this time. The vehicle will turn over, but won't start at all. I am having it towed to the dealer today and I am looking for some areas to ask them to check. PLEASE HELP!!!

  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    Hey Brian,

    If you wanted to get us your case number, we would like to look into this further. It would probably be most efficient if you wanted to email it over to (please include your Edmunds username, and perhaps even a link to the post so we make sure to include everything -- my coworker Christina answers inbound emails).

    All the best,
    GM Customer Service
  • Wow, so glad I found this site. I bought this 2005 new and 3 weeks after I got it my electrical issues started. They have been going on for 7 years. I wish now I had taken it back to the dealership and demanded my money back or contacted an attorney in Arizona because of our lemon laws. Being a recent widow when I bought this, I just never thought that a dealership or a company could be so dishonest. :lemon: :lemon: :lemon: :lemon: :lemon:
    So, coming home from a funeral 200 miles away I hit a little bump on the interstate, my door locks started clicking locked and unlocked, my instruments went crazy and I lost engine power. After I finally got it to the side of the road and turned it off, I set there of a few minutes and when I restarted it it ran fine. Ran fine for about a week then it left me stranded on the side of the road.

    I have moved from a large metro area to a small rural area so we do not have a dealership here. (Don't think I would use a GM dealer anyways). My mechanic has driven the 200 miles to me and has been going over my vehicle for 2 days with a fine tooth comb. I will let you know how he resolves this if he is able to. I called GM and got an incident # on this. The last time I was given an incident # was also electrical, but because I was in an accident due to their proven faulty wiring they jumped through hoops to try and get things resolved.

    Spread the word, DON'T BUY GM PRODUCTS. They not only don't care about the crap they sell, they could care less about you. They lied when I called them and stated that they didn't have any other incidents like mine in their records. And then I find this site with all the comments from GM Customer Service Agents. They should be ashamed.
    I wrote a $50,000 check for my Yukon. They can kiss this GM customer goodbye as well as my 5 daughter and their husbands.

    They aren't going to admit that their vehicle have any problems until there is a significant number of deaths involved. I don't want to be one of them. Just want to get this fixed so I can get rid of it.

  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    I'm glad to read you've already gotten in touch with us by phone about this, but am sorry that it had to be under these circumstances.

    If you want for us to look into any updates on your Service Request, feel free to send us the case number and we'll be happy to do so!
    GM Customer Service
  • OMG!! My problem was exactly the same as avanti274. Actually broke down for good on I-75 near Lake City, FL. A local repair shop hit the nail on the head... Need a new catalytic converter. $800 later(part only) it runs like a champ. That was over a month ago. My Tahoe is a 2003 with 150K miles on it. Warning: don't buy an after-market part. I heard they don't last nearly as long. I don't know if this will help all who posted, but even if it helps one, it's worth it.
  • avanti274avanti274 Posts: 2
    Hi dawginole,

    Thank you for the post! Can you please elaborate more specifically on the problems your Tahoe had before you replaced the catalytic converter? I would love to get my Denali fixed.

    Thank You!
  • zurizuri Posts: 1
    This post was a blessing to me & I just wanted to THANK YOU so much. I was at my GM Dealer and they were about to charge me $798 to replace my throttle body on my 2009 chevy malibu, and informed me it was not covered under warranty. My heart hit the floor. I told them I needed a minute because that price was outrageous. I set down in the waiting room and google throttle body, power train warranty and GM, and a link to your post was the first thing to pop up. After reading it I immediately called GM verified the warranty info., and they called the dealership and got everything squared away for me and got me a rental reimbursement because the part was under warranty. What a blessing this was to me. Thanks again.
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    I'm glad to hear you were able to get everything worked out - I'm sorry that you had to go through this experience, however. Is your vehicle still in the repair process, or do you have it back?

    GM Customer Service
  • I hope people read this before going and changing there throttle body. Our 2003 GMC Sierra 2500 6.0 started started up about 8 months ago. We changed the throttle body, among other things and it was good for maybe a couple months and now its doing it worse than ever. My husband has checked the wire harness, cleaned the cables, and so on. I refuse to take it to a GM dealership after reading all of these. DONT EVEN WASTE YOUR MONEY ON THE THROTTLE BODY, OR THE TPS. We even changed the fuel pump. So if anyone has come up with a solution I would love to hear it. :mad:
  • When you change the Throttle Body was it a new part or a refurbished part. The reason I ask is I to changed the Throttle Body but used a refurbished part, it wasn't until I replaced it again with a new part that the proble went away it has been more than a year now with out an issue
  • stephc1stephc1 Posts: 6
    I posted on this thread years ago about my 2003 YXL that reported reduced engine power and died on me. My vehicle was eventually repaired when a mechanic replaced a clamp on one of my ground wires. It is still running fine many years later...I never had another issue with it other than having to do general maintenance. If the clamp seems okay have your mechanic check the wires because they seem to deteriorate and cause all kinds of issues with the computer (mine sent error messages for everything imaginable when it had a problem...including TBC). Good luck everyone!!
  • cubbearcubbear Posts: 3
    I have previously replaced the Throttle Body and Throttle Body connector with 18" pigtails. About $1,100 total. Plus, I have tightened ground connections, added TB cleaner to my gas, added moisture removal chemicals to my gas, and put on a new gas cap.

    Today I replaced the TB cable myself with P/N PT2628 with 18" pigtails purchased from for $75.80 which included S/H. I tinned the wire ends, slipped shrink tubing over the pigtails, used a crimp on sleeve as a splice, soldered the wire connector after crimping the splice, then shrunk the tubing to insulate the connections. I used a heat resistant tubing to fit over the entire cable. Being an electrical engineer before retirement, I did it right. The wiring cable and connector were about 10X the quality of the GM factory cable and connector previosly installed by GMC about 2 years ago. But, much to my dismay, I drove the truck about 100' before a return of the REP.

    Today, after the return of the dreaded REP, I cleaned my old TB that I kept after it was changed the first time. I did a very thorough cleaning of the TB and even removed, polished, and then aligned the butterfly valve. Then I noticed what could be the problem that has been dogging all of us. The male connector on the Throttle Body itself has two nickel plated pins (1 & 3 from top left) and eight gold pins. In engineering we used to have nothing but trouble with nickel plated pins and corrosion and afterwards always specified male and female connector pins of gold. It looks to me as though GM found a way to save 30 cents in cost instead of doing the right thing. The female pins on both the old and new cable connectors were gold. I cleaned all the contacts and will install the newly cleaned TB this weekend. I'm actually going to GMC in the next few weeks and look at a new TB and see if the contacts are now gold.

    I've got to find a solution soon because my inspection runs out this month. No way it would pass inspection even if I could get it to run for more than 15 minutes without REP. Right now it is a real danger not only to me but to others.
  • So previously I have posted my frustration with the REP and throttle body problems with my 2007 GMC YUKON XL.

    I have also expressed my absolute disgust with GM's response to the many problems that I have had with my vehicle since it was purchased new.

    My vehicle needed a new battery every year until the problem suddenly stopped. The dealership never acknowledged a problem or said what they did to correct the problem. They just kept putting in new batteries.

    When I complained about EXCESSIVE Oil consumption the dealer told me that it was well within the "guidelines". Now that my vehicle is completely off warranty and still going through oil, the dealer is telling me that there is a bulletin out regarding an engine part that malfunctions and it would only cost a couple of thousand to fix the issue.

    I hope that people are reading Edmunds before the ever buy a GM vehicle!
  • I hate to say attorney because that is the very last resort. I went through a lemon law attorney and GM finally agreed to a buyback. Most attorneys will review your case at no charge, but you have to know that you are going to have to buy a new car. GM finally agreed to a buyback through a lemon law attorney. It worked out that I got more than the trade in value. You should call one and depending on the state you live in they may be able to help. I am so happy to be rid of the problems even though I have a car payment now. I feel much safer with my kids. It was worth it for me. Good luck.
  • yukon11yukon11 Posts: 2
    I was driving on the highway going about 75 miles and when all of sudden my 01 GMC Yukon stalled on me showing REDUCED ENGINE POWER, the issue I have with this is I had this problem about 9 months ago and had to replace the throttle body which is very costly and now I'm
    having this issues again not even a year later. Due to the number of complaints I see via e-mail and online, GMC should consider investigating the THROTTLE BODY before someone gets seriously hurt or killed.
  • dob49737dob49737 Posts: 1
    edited July 2012
    do you know where that ground wire clamp was?....I had one attached to a black wire right behind the engine, going towards the engine block in the rear,,,,,i wiggled it a couple of times and the end loop piece just came off....I reattached some wire to the black/white striped wire and attached it to the firewall.....only time will tell.....

    If you can let me know where that clamp was i would be grateful.

    I will report if any further problems occur....
  • Is this problem with just the older models or is it the same way with the newer models as well. Basically I have a 07 with 73 k so I'm out of my bumper to bumper warranty but its going through the whole engine reduced problem every couple of days. Of course when I went to the dealer the supposedly fixed but I don't want to dump any more money in this truck. If this isn't a problem with year 10 and up I'll just get a newer vehicle
  • Update on my 2003 suburban with 250k. No longer my daily driver. Reduced engine power light originally just happened when the weather was sub zero. I live in Austin now so not much cold weather, however the same thing happened the other day, pulled on to the service road and accelerated to 60 mph and then 'ding, ding, ding, the engine went to idle and reduce engine power illuminated. I pulled over(luckily traffic not to heavy) turned off the engine for about a minute and started it up and it ran fine. I'm reluctant to do any repairs because on this forum it seems most people get the throttle body replaced and the same issue continues. I'm still searching for a permanent solution if there is such a thing.
  • cubbearcubbear Posts: 3
    In a previous post I listed all the items I had done. Then I took it to a local auto repair shop. They promised me if they couldn't fix it there would be no charge. Well, they kept it three days and couldn't fix it. True to their word, no charge. When I got it back home it was running really rough and the REP warning was on plus the check engine light. While it was running, I started wiggling wire harnesses. Like magic, when I wiggled the harness against the firewall near the fender on the drivers side down low - low enough I could barely see what I was doing with a flashlight and the engine would start running okay and then rough again. I wiggled it again and it quit. No problem for several weeks - running like new. I drove it to the dealer because the check engine light was still on. They could see the codes but could not duplicate the problem. If it happens again, they said take it in immediately with moving the wiring harness so they could verify my finding. Plus, with all the money I have spent, they will repair it for no charge. How about that!!! I'm hoping it never happens again.
  • gmcustsvcsarahgmcustsvcsarah Posts: 1,964
    We're glad to see that you've been able to find a resolution for the rough running engine concern you had had. All the best!

    GM Customer Service
  • I would be more that interested if this could turn into a class action suite. Would like to be kept informed.
  • i have a 2004 tahoe , im driving in mexico , reduced engine power , abs and check engine lite comes on dash , nobody here can tell me whats wrong , been stuck here for a month , visa running out can you help me truck wont start , battery starter alternator all good , codes ok please i need your help robbie
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