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GMC Yukon Reduced Engine Power message



  • Have you had any mores problems with the reduced engine power light coming on since you changed the gas cap ?

    Thank you
  • Please help my 2003 is doing the same thing. reduced engine power, stability message traction control light and engine light. Truck slows to 25 mph. Is the 2003 having the same issue as the 2007 to 2011 models or is it different?
  • I have not had any of the 2007 - 2011 with the reduced power problem.i have had some with the active fuel managment system problem where the lifters go bad and they will wear a flat spot on the cam.when this happens the truck will miss fire real bad.the reduced power with your truck will either be the throttle body , the wiring harness at the throttle body plug , the throttle position on the gas peddle , or the throttle control module on the fire wall , or the wiring harness from the peddle to the module.the wiring harness will sometimes have a broken wire in the plug section at the throttle can use an ohm meter to check the harness just unplug it at the module and at the throttle body and check the wires between for continnuity.
  • ebonyhebonyh Posts: 5
    edited September 2013
    I am SICK of dealing with this problem. I wish there was a class action suit to get this taken care of! We paid $600 two years ago to "fix" this problem. One year later, we get reduced engine power again.

    IT IS A KNOWN ISSUE and GM does nothing. I am so upset about it. I think I have posted somewhere on here before about this. Why don't they fix this for FREE?
  • Hi Autotek44,

    I have had all of the reduced engine power problems, and the excessive oil consumption problems and am now getting oil fouled plugs from another engine problem. What was the fix for the misfiring on your truck....just replace the lifters. Have you had any problems with the plugs getting oil fouled.
  • gmcustsvcgmcustsvc Posts: 4,251
    Hello ebonyh,

    I understand your frustration with an ongoing reduced engine power vehicle issue. Each customer is looked at on a case-by-case basis. I would like the opportunity to further discuss your situation. Please email us at socialmedia(at) and include your full contact information, VIN and current mileage. We look forward to hearing from you.


    Laura M.
    GM Customer Care
  • Haven't posted in a while, so here is my update;

    I have had the reduced engine issue for over two years now.
    I have changed and cleaned the K and N air filter,
    replaced the mass air flow sensor($70 or so at Auto Zone)
    replaced throttle position sensor($60 or so at Auto Zone)
    used a rag and throttle body spray cleaner and elbow grease to clean
    the interior of the throttle body(have to remove all the air intake plastic pieces)
    replaced the fuel filter
    put in numerous throttle body cleaners with the fuel;
    some of these worked but I would continue to get the 'reduced engine power',
    95% of the time this would happen in the morning and only when the nighttime temperature dropped 10 to 20 degrees. I would pull over, turn off the vehicle,
    let it sit for a minute or so and then restart and drive the rest of the day without issues most of the time.
    I haven't had any issues in the last six months(summertime), however when it cooled down a few weeks ago the problem has resurfaced so back to the drawing board and researching. I've been to a few dealers and all they want is to do a $100 diagnostic, I always reply that I can do that free at autozone, I would prefer a remedy for the problem.
    Anyway, I read in one of the posts here to replace the gas cap. I did a week ago and the 'reduced engine power' has not come on. Crazy! if it's just the gas cap I am amazed.
    I hope this helps. The gas cap is a 'stant' from amazon for about $10.
  • ebonyhebonyh Posts: 5
    Dear Laura,

    I am back to report that after waiving the diagnostic fee and getting a 20% discount, we paid about $480 for the same repairs they did almost 2 years ago.

    We got the Yukon back last week, and today WE STILL HAVE REDUCED ENGINE POWER! That makes about $1000 we've paid in the last three years to have GM certified mechanics NOT fix this deadly problem.

    I don't know what kind of shop they are running or what kind of customer service GM thinks it has, but this is not it. I am contacting GM one last time today. Honestly, we should not have had to pay for the same solution twice!

    Anyone else have to deal with this nonsense?
  • ebonyhebonyh Posts: 5

    Even with this government shutdown- PLEASE fill out the form- no matter the make or model of your GM vehicle. I searched for a previous submission on our model Yukon and was surprised to find another owner posted just yesterday.

    NHTSA forces these companies to recall faulty products. If any of you have been injured or if you know of anyone killed in an accident to to REDUCED ENGINE POWER, please click YES on those questions.


    This may be your first step in making sure GM takes care of its customers.
  • Well my reduced engine power problem has seemed to sorta go away by replacing the wiring harness twice, but now somehow the wires to the running light got fried, the temp reading on the rearview mirror is flashing all the time and now the engine doesn't want to start sometimes and its not a battery issue...I have a feeling that the wiring harness is going bad again but nobody wants to believe me..I was told it was a certified GM part they don't go bad....what a joke!!!!
  • As previously mentioned my latest endeavor with the reduced engine power issue was to replace the gas cap, however, went into reduced engine power mode again, only once so far, I will continue to update as it occurs.
    I may replace battery cables next unless someone has another suggestion.
  • ebonyhebonyh Posts: 5
    Once again, GM has replaced the pedal sensor three times now. Just got the car back last week and guess what? It happened again. Back to repair a FOURTH time. This is a bunch of BULL. It's not the pedal sensor!
  • My dealer had to build a wire harness from the throttle body to the pedal. Or how ever the wire harness goes. They built a replacement from scratch. Why? Because GM doesn't sell one for replacement! They also replaced the throttle body. But if I had to bet money on what fixed it between the two parts. I would have to say 98% sure it was the wire harness. I think GM got some cheap wires/wire harnesses made in Mexico. And the poor quality of that product would severely hurt their bottom line and they know it. In fact the GM rep. on the 1-800 number was a jerk. And got real nasty after I asked about getting an attorney after my Denali quit and almost put me and my family in a wreck. He was so bad that what ever email he sent to my dealer service writer, really made him upset. As a result my service writer completely took care of the situation. That was like two years ago or more. GM has a BIG WIRE problem they need to own up to it! Tell your dealer to replace or build the wire harness from the throttle body to the gas pedal. Don't fall for the gas cap thing either. Never changed mine and owned our Denali since new in 2003. Hope this helps.
  • Hey, I need to get my truck fixed. This problem has been driving me crazy! Who is your dealer and how do I get my dealer to understand this info because obviously most dealerships are not on the same page when it comes to this problem. Also when did it get fixed and have you had the problem since?
  • I have had the SAME problem. Reduced Engine Power when the temperature changes. I have had the throttle position sensor changed twice. This last time they changed some wire harness. It is still doing it. More now whether the temp is cool or not. Have you figured anything else out? I am very very frustrated with this ordeal.
  • I too am having issues with my 07 Yukon.

    This may sound crazy...but with all the computerization, maybe not, but has anyone found a correlation with this problem occuring and oil levels?

    I first had issues in August. Just prior to getting the dreaded 'reduced power' message, I was getting a "low oil" message/warning. However, dipstick showed proper oil level and I attributed it to a faulty sensor. About three weeks later my wife got stuck on I287. I had not done any research, just figured that a low oil condition would send the car into 'safe' mode so I replaced the sensor and the problem went away until this week.

    I was very much up for an oil change and the truck again slowed down on my wife, coincidentally the same time as the change engine oil message came up.

    I'm not about to go about throwing parts at this thing as many as you have. I have no justification for it, but my gut tells me its related to some kind of computer/programming snafu.

    Anyone else see something similar?
  • dillmandillman Posts: 2
    edited November 2013
    Ok, I have a guy that works on my truck out of Broken Arrow, Ok. He is good. As my brother has told me, if this guy can't fix your pretty much screwed. He is that good. BUT, HERE IS THE INTERESTING SCENARIO.

    My Truck is still doing the "reduced engine power", but only at certain speeds. Here is the deal.....when I give it gas and take off and then let off staying at or below 30mph (coasting) it doesn't go into reduced power. ALSO, when I get out of town and throttle the truck up past 60 it doesn' do it either. If I go below 60 and then try to give it gas, REDUCED ENGINE POWER!!! If I stay above 60 the truck has ran good (knock on wood!) BUT, if I try and stay beween 30 and 60, it is a consant headache...REDUCED ENGINE POWER.

    So, I called "my guy". I told him my little scenario. He is going to research it a little more. He thinks it could be related to a wheel bearing. Something in the wiring in the wheel bearing/tire area and relating to the signals that are sent to the brain/computer of the truck. Sounds kinda strange but he seems to know A LOT more than I do!!
  • Buy cheap odb2 code reader from harbor freight tools. Hit the clear codes button and it will return to normal, I have an older model reader with a clear codes button. I think it was $39. Keep the odb2 sensor plugged in if you plan to drive the vehicle with this problem as it can be dangerous if you get the "reduced engine power" code in traffic or on the freeway. I almost got rear ended last week on the freeway. Now if I get the code I hit the clear codes button it it returns to normal without pulling over and turning the truck off.
  • Hello everyone I am a mechanic and i have had this problem in my shop a few times. I have stated here in this forum before there is more than just one cause to this problem.I have found five different fixes.
    1. throttle body
    2. throttle body wiring harness at the throttlebody
    3. the pedal position sensor
    4. the pedal position wiring harness
    5. the throttle control module

    I also know that not all year models have a throttle control module and a replacable pedal position sensor wiring harness.
    The gas cap will not fix the problem and using a code reader to just clear the code is a bandaid fix not a proper fix.
    I have also found on some vehicles that one or more of these are the problem.The last one i fixed was almost a year ago no more problems.
  • I too have had the dreaded and terrifying "Reduced Engine Power"/"Service Stabilitrack" error. I have a 2007 GMC Yukon XL. It eats oil for breakfast and shuts down randomly. I have a TPS wiring harness on order and will be in tomorrow (12-3-13). I have been told by a GM Dealership that I have to have a computer to reset after switching out the wiring harness. Can anyone tell me if this is true or they trying to pull one over on a blonde woman. I love my Yukon but I'm about to trade it in on a Ford Super Duty with the troubles I've had. Always been a GM buyer but I'm about done with them. Way to dangerous for my family.
  • Just returned from a deployment where my car sat for about 4 months. When I finally got back into it, it drove fine for a bit and then I started getting "service suspension" message and the check engine light was on. I took it into Autozone to get some supplies and had them hook up the diagnostics. Error codes P449 and P045 came up relating to the gas cap and possible solenoids or vapor canister. Basically the gas cap wasn't tight or I was topping off the fuel and some went into the vapor canister... no big deal, just tighten the cap and disconnect the negative terminal on the batt for about 15 seconds and the computer will reset the check engine light. NOTHING addressed the suspension issue. So driving to work this morning and at a stop light my dash started chiming and "stabilitrak disabled", "traction control disabled", and "reduced engine power" came up. Took off from the light and it was rough. I pulled into a parking lot and looked up some stuff on the net. I was letting my car sit while off when I heard a "click" so I tried starting it and the warnings were gone but the check light was still there. But it ran fine so I continued on to work. About a mile down the road, it all happened again as I took off from another stop light. So I pulled over and called a tow truck. I was researching stuff and was going to have it towed to the house where I would replace the throttle body sensor, clean the throttle body, replace it, or whatever. Mind you, it started up no problem. Then the tow truck got there and it wouldn't wouldn't turn over at all! He started telling me it was the starter! So I changed my mind and had it delivered to the GMC dealer service center where I await a diagnosis...
    I've read everything from it's a dirty throttle body to the computer needs to be reprogrammed. Anyone else experience this series of issues? I feel like I'm looking down a rabbit hole and I'd rather not fall in regarding the issues you all below have run into. - Vince
  • I have a 2009 Yukon with the same Engine Power Reduced and runs terrible. I have been an avid Yukon owner for the last 12 years. I'm now done. I am trading my current yukon in and will never purchase another GMC product knowing they do not stand behind there vehicles.
  • Glad to discover this forum. I thought I was alone with this problem. My wife is scared to death to ride with me anymore, fearing that the feared "Engine Power Reduced" message will flash up once again telling us what we already know!

    After having the both the throttle body and the ECM (both rebuilt) replaced by my local garage due to first a complete failure to idle and then a rough idle and this issue, I took it to my local GMC dealer. After having it for 3 days they still couldn't 'duplicate' the 'condition'. I volunteered to show them exactly what happens upon the first start-up of the morning. Sure enough, happened with the 'technician' in the truck less than a mile from the dealership. Could they fix it? Did they even indicate that they had done something as simple as perform the search I just completed on the web? Of course not! They printed out the trouble codes for me and washed their hands like it was Easter and I was you-know-who. But at least I have most of a vehicle to drive. My service display gives me these codes about, oh, ONCE A DAY!

    Please, someone from GMC, get in touch with Brogden in Olathe, KS and tell them what's going on here. If there is a fix, will you please let me buy it? Or are you keeping your dealerships in the dark on this issue? Is this some sort of poison-pill secret corporate-level-planned-obsolescence built in to these trucks to get us to trade up to a newer model? Well, it won't work in my case. I'm on a fixed income and this is my last SUV, ever. I'm sick of it and my wife's scared of a truck she used to love because it has such great seat heaters.
  • littlewoodylittlewoody Posts: 2
    edited December 2013
    Laura M. Please read my post of earlier this evening (587). If there's a fix for this, I need it before I try to pull my 32' trailer to AZ with my '03 Denali. Thanks.
  • Has someone found a solution to this because the GMC dealer keeps charging me money to "fix" the issue but it's still happening. If everybody is having the same issue, then clearly it's has to be an issue with the vehicle and a recall should be done! It's very dangerous and I have been afraid for my life many of times because of this issue. The GMC dealer replaced my throttle body, no such luck. Took it back and they replaced some ground wires, still no fix. Took it back a 3rd time and they said it was my TAC module, they replaced it, still NO FIX! Each time costing me hundreds of dollars! I refuse to keep taking it back paying money and it's not solving the issue! Isn't that illegal? I'm confused on how you make a vehicle, but you have ZERO idea on how to fix it when something goes wrong. And clearly it's not a one person issue, so it's something faulty in the makeup! I'm so irritated! Any suggestions? Has anyone that had this issue, fixed theirs completely?
  • The only solution I have found is to buy Ford. You're right, this should be taken care of, but it isn't and it's dangerous. GM's answer is to put some very nice social media reps on this forum in hopes of keeping people calm. We still have our Tahoe, but replaced my Silverado with an F150. The Tahoe will be the next to go to a Ford.

    Good luck djswifey.
  • I tried everything!!
    I didn't get any very nice social media reps contact me!
    I too, had to (guiltily, because I had to give someone else my problem) trade it for a Toyota.
    I couldn't take it any more!
  • zwupzwup Posts: 1
    I have the exact problem here. I thought when I could not start it at all that it was related to the security system. The security light stays on and cant lock or unlock doors unless the key is in and on.

    Usually resets between half an hour up to two hours.

    Tonight it went into reduced power mode. I made it home about 3 miles from town but live in a mountain area. I was down to 15 to 20 miles an hour and lucky to not get hit. Well maybe it would be better if I get pasted then I can junk this piece of crap and by a real vehicle. NOT GM!!!!

    I have been GM almost 100% but after seeing how they build cars now no more GM for me....

    I have had it at dealer and 4 outside repair shops... so far about $1500 in and it is as bad as ever.
  • I have a 2007 Chevy Avalanche with high mileage. This reduced engine power issue started to occur about 6 months ago. The issue would seem to take place in spurts. It wouldn't occur for a few weeks and then it would happen several times over a few day period. My wife wouldn't drive the vehicle so I became very adept at removing the battery cable waiting a few seconds and then reattaching. This would always correct the issue for a while but became very annoying as it would seem to happen at the most inconvenient times.

    The issue started when the vehicle had about 175,000 miles on it and at 197,000 miles I decided to order the direct replacement throttle body from Rockauto. I didn't decide to change the throttle body until I read all of the comments listed here. It seemed to be the most logical fix for the 2007 model year as compared to many who have had the wireharness type of causes. The throttle body cost me $167 including a new gasket (which you won't need) and shipping. The replacement is very easy and took me 30 minutes to do myself. I'm writing this now after almost a full month of no issues. Since my vehicle has high mileage, the replacement of the throttle body which was relatively dirty has improved the responsiveness of the vehicle. So far so good... If anything changes I'll post another note.

  • nukstrnukstr Posts: 4
    edited December 2013








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