2003 GMC Yukon Denali: sudden loss of power

Filed Nov 27, 2018 · Driver assistance · 170,000 miles · CT

Loss of power without warning , while on highway. From 65mph to 0 without warning. Almost caused a crash pile up....was almost rear ended. Very dangerous...whole family children and all was in the vehicle.

Filed Mar 21, 2018 · Acceleration, Driver assistance · 152,000 miles · NV

I have a 2003 yukon denali I purchased and it has given me the reduced engine power light and almost had a few accidents on the highway because it drops the speed to 20 MPH also it has the check engine codes as p0120 and p2135 I have been aware that gm has not found a solution to this and wanted to see if there is any recalls as I am very afraid of being in a very serious accident with my children in the car. The consumer stated the vehicle was repaired and requested withdraw the complaint.

Filed Jul 23, 2014 · Engine, Transmission · 220,000 miles · AL

Tl* the contact owns a 2003 gmc yukon denali. The contact stated that the vehicle decelerated and stalled. The reduced engine power indicator illuminated. The vehicle was taken to the dealer six times to repair the throttle body, pedal switch, and wiring harness, but the failure recurred. The failure mileage was 220,000. Updated 10/02/14*lj updated 3/9/2015

Filed Mar 6, 2014 · Engine · IL

We have a 2003 yukon that will shuts down anywhere and anytime, the following example has happened more than once. We were driving on the highway when "reduced engine power" "stability traction loss" appeared on display - I pressed the accelerator and the vehicle would not move. I had to completely shut down the engine wait a few minutes then restart in order for the vehicle to operate correctly and a couple miles down the road, it happened again. It was a snowy mess out side which made the situation worse. This is a major safety concern as I am unable to accelerate in order to avoid an accident. I get scared because there could be a semi behind us and it will just plow into us because we can not do anything until we shut down the engine and restart. Very scary. We researched this issue to find other people are in the same situation and no one seems to know how to fix it. This is a long standing issue, gm is aware of this issue but will not issue a recall. Gm seems to be having alot of problems that they are not dealing with. Shame on gm!

Filed Feb 6, 2014 · Acceleration, Electrical · 125,000 miles · MO

Driving on hwy going aprx 65mph. Vehicle said reduced engine power and started slowing down. I had to pull to side of the road. I managed not to be rear ended. This has happened often. It is a potentially life threatening situation. Gmc know about this problem and how difficult it is to find the proper fix. Someone is going to die due to their lack of action. It's not safe.

Filed Dec 30, 2013 · Engine · 213,000 miles · NY

Tl* the contact owns a 2003 gmc yukon denali. The contact stated that the traction control and the reduced engine power warning lights illuminated and caused the vehicle stalled. The contact was able to restart the engine, which resumed normally. The failure was recurring. The vehicle was taken to the dealer, who was unable to diagnose the failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure and current mileage was 213,000.

Filed Feb 12, 2012 · Transmission · 135,000 miles · WI

We were driving at highway speed and lost power with no warning. I coasted to the side of the highway avoiding one collision. I had it towed back to home. The dealer had to clean the throttle body. I contacted gm and asked where was this cleaning for preventive maintenance. They could not answer. I am fearful for others who have this type of vehicle. Without cleaning the throttle body others will have this problem too. I went to several internet forums and many others have stated this problem. Http://townhall-talk.edmunds.com/direct/view/.f0e807e/227 please help! [xxx] information redacted pursuant to the freedom of information act (foia), 5 u.s.c. 552(b)(6).

Filed Dec 16, 2011 · Driver assistance, Electrical · 97,000 miles · GA

I have had multiple ongoing electrical issues with this vehicle. Starting in 2005, the exterior electronics (I.e. Signal lights, stop lights, head lights, etc) began to malfunction. For example, I would trigger the signal for one direction and all of the signals for all directions would trigger... Even pressing the brakes triggered all of the exterior signals. The dealer had a hard time isolating my problem, but after several visits, the dealer was finally able to diagnose and rectify it... They isolated it to a junction box where all of the electronics terminate. However, by this time, my vehicle was out of warranty, so I had to cover the costs for repairing the problem myself. My most recent issues, which, by the way, seem to be common issues, are triggered by a message stating, "reduced engine power". This particular issue does not always render the same results... Sometimes the vehicle's speed will significantly decrease to nearly a halt, but other times I may just experience increased idling of the engine, even if I am at a complete stop. My understanding, according to hundreds of reports that I have read on the message boards, is that this issue is caused by either a wiring harness that leads from the accelerator to the throttle body or it's a defective throttle body altogether. I have experienced intermittent electrical problems with my windows as well, but this appears to be a minor issue when compared to the other two that I addressed above. I will file a formal complaint with gmc corporate office today and see where that goes.

Filed Nov 22, 2011 · Driver assistance, Electrical · 117,000 miles · OK

December 2008- instrument cluster went out- speedometer no longer working december 2008- battery gauge no longer working march 2009- stabilitrak issues...sometimes the stabilitrak would work and at times it would not work july 2009 to january 2010- reduced engine power (almost cause 2 wrecks) could not perform a diagnosis...could not read computer. Changed fuel pump. No more reduced engine power message august 2011- wheel bearing issues. Reduced engine power (almost caused wreck...backed up traffic) september 2011- gas pedal sticking november 2011- reduced engine power...happens 5 times within a 30 mile trip. Attempted to resolve problem several times, but running out of options. Have to kill car in middle of highway or intersection to get car to work properly.

Filed Jul 15, 2011 · Engine · 159,906 miles · AZ

Randomly, the truck will go from driving completely normal to getting a message saying "reduced engine power" and then it cuts off power. This has happened 10 to 12 times, the last time it happened I could not drive more than approx 35 MPH even with the gas pedal floored. We have replaced the supposedly defective part(s) to no avail.