GMC Yukon Reduced Engine Power message

rcmedic

I have a similar problem with my 2005 Suburban 2500 LT. I too have been dealing with this problem for over a year. I initially got OBII codes of P2135 and P1516. After going through all of the recommendation that I have found on the internet forums and etc, I have been unsuccessful in correcting the issue. Early on I replaced the Throttle Position sensor on the accelerator itself, then the throttle body as well as the throttle position sensor (TPS) on the throttle body and the electrical harness to the TPS. When none of those worked, I next went through and cleaned all of the connections and grounds including those on the control module next to the washer fluid reservoir at front of the drivers side fender. That changed my codes from those mentioned above to P1125 and P2120. I am not really sure where to go from here. The only thing that I am very certain about is that the problem is electrical in nature and probably due to a bad ground but I have not been able to locate and so also have not been able to fix the problem. I am looking for ideas and feed back.

jenniferdennel

lynniewags said:

The worst winter in Chicago was also the worst winter with our 2004 Yukon Denali - after babying the beast for years, I have had it. The Check Engine light is on continually, the Reduced Power due to the Stability Control occurred Friday evening on the I94 with 4 kids in the car - almost gave me a heart attack. I read the posts from 06 and will bring to a reputable mechanic to check with Wiring Plugs on the Throttle Body, Front Abs Sensors. I was trying to get another 2 years out of the Yukon - but at this point, I will sell it for parts and buy a Ford. Between this and the Brake Lines snapping last summer - I am done. You would think GMC would be forthright on what people are reporting as "potential problems" and what they suggest as preventative measures that should be taken especially with late model vehicles. My truck wears with honor the badges of the places we have visited - ski trips, family vacations, road trips hauling the boat. This is leaving a nasty taste in my mouth and I am looking at other trucks instead of going back to the one I have enjoyed for so many years. 2 Potential Life threatening incidents in one year is a tough pill to swallow.

Same truck same issue took me over a year and thousands of dollars to finally resolve GMC electric throttle body's are faulty the fix is to have your mechanic convert your throttle back to the old school cable that goes to the gas pedal it's been two years REP free this is the fix 

lee2113

I have a 2003 GMC Yukon Denalli. I bought it with 264,500 miles yes that is correct. I've driven it another 2,000. miles. Took it to national department store chain, for a wheel alignment. They found plenty wrong with tirods, ball joints etc. Didn't have them repair it. After I left the shop I had the reduced engine power, twice. It did start again. I've had all the other work done at another shop and am going in tomorrow for the wheel alignment. I will see if I have problems again. They will not be repairing it. I thank everyone for their responses. I will have someone check out your repairs you suggested. I will post again after I check all of this out.

Mr_Shiftright

Be sure that the ball joints and tie rods are safe--if either fails completely, that would be *very* dangerous. A good shop should be able to tell you, or SHOW you, the amount of play in the ball joint as well as the specification in fractions or millimeters as to what is acceptable play. (a little play is ok in a balljoint but a tie rod that is loose must be replaced).

davegmc1

Mr_Shiftright said:

Be sure that the ball joints and tie rods are safe--if either fails completely, that would be *very* dangerous. A good shop should be able to tell you, or SHOW you, the amount of play in the ball joint as well as the specification in fractions or millimeters as to what is acceptable play. (a little play is ok in a balljoint but a tie rod that is loose must be replaced).

Hi, Everyone, I have the same problem while my 2007 Yukon at around 40000 mils (2 years ago) , and this bother me few months and ready a lots of forms and even visit GMC dealer, they have no clue.
And one day I decided try the #93 gas instead of #87 I used for years. You know what, I am now trouble free from 'Engine Power Reduce' problems for over 30000 mils. And my engine light never light on again and my Yukon runs like a charm.

If you still have ''Engine Power Reduce' problems, please try #93 gasline, and you might find yourself a solution.

I hope everyone ready form can share this information, it might help you and your friends.

Thanks.

davegmc1

bonddog said:

I purchased my 2006 Yukon last September 2005. I now have 24,000 miles on it. Over the last month I have had it into the dealer three times for the same problem. The problem is that while driving the vehicle it will suddenly lose almost all power. The Information Center will display the messages: "Stability Control Disabled", "Engine Power Reduced". And the vehicle will not go over 20 mph on a level surface and bearly 3 mph up a moderately steep hill. Each time I have had it into the dealer for repair they have beeen stumped by what the cause of the problem is. They said that GM/GMC told them that "GM is aware of the problem but does not have a fix for it at this time". How can a manufacturer sell a vehicle that has a defect and not have a fix for it? When the power goes out in a busy intersection or on a highway this is a major safety issue. Has anyone else experienced this problem.
Thanks, Steve

See Also: Reduced Engine Power Message Displayed on GM Vehicles

Hi, Everyone, I have the same problem while my 2007 Yukon at around 40000 mils (2 years ago) , and this bother me few months and ready a lots of forms and even visit GMC dealer, they have no clue.
And one day I decided try the #93 gas instead of #87 I used for years. You know what, I am now trouble free from 'Engine Power Reduce' problems for over 30000 mils. And my engine light never light on again and my Yukon runs

If you still have ''Engine Power Reduce' problems, please try #93 gasline, and you might find yourself a solution.

I hope everyone ready form can share this information, it might help you and your friends.

Thanks.

davegmc1

bonddog said:

I purchased my 2006 Yukon last September 2005. I now have 24,000 miles on it. Over the last month I have had it into the dealer three times for the same problem. The problem is that while driving the vehicle it will suddenly lose almost all power. The Information Center will display the messages: "Stability Control Disabled", "Engine Power Reduced". And the vehicle will not go over 20 mph on a level surface and bearly 3 mph up a moderately steep hill. Each time I have had it into the dealer for repair they have beeen stumped by what the cause of the problem is. They said that GM/GMC told them that "GM is aware of the problem but does not have a fix for it at this time". How can a manufacturer sell a vehicle that has a defect and not have a fix for it? When the power goes out in a busy intersection or on a highway this is a major safety issue. Has anyone else experienced this problem.
Thanks, Steve

See Also: Reduced Engine Power Message Displayed on GM Vehicles

Hi, Everyone, I have the same problem while my 2007 Yukon at around 40000 mils (2 years ago) , and this bother me few months and ready a lots of forms and even visit GMC dealer, they have no clue.
And one day I decided try the #93 gas instead of #87 I used for years. You know what, I am now trouble free from 'Engine Power Reduce' problems for over 30000 mils. And my engine light never light on again and my Yukon runs

If you still have ''Engine Power Reduce' problems, please try #93 gasline, and you might find yourself a solution.

I hope everyone ready form can share this information, it might help you and your friends.

Thanks.

gmc_wastemoney

My 2006 envoy denali has cost me 3x the purchase price with same issues faulty gas guage, shattering rear window, stabilitrack issues have fixed 5 times. Dealership and Gmc deny any of the recalls and only keep costing me money. The stabilitrack and loss of power has caused 2 spinouts now and i should be dead. There is no accountability with them!!! 

Dont buy GMC anymore!! They are worse and more negligent than cadillac that cant make a bumper stay on their cars which is much less hazardous!

We need to stop them before someone dies

lamarrsullivan

I have a 2003 GMC Denali that has sat in my garage for almost 2 years because of this problem. I was never afraid to spend the money to fix this issue but my problem was spending $1K to $1500 and still having the issue. Well, Finally I did end up spending $1300 last week. I spent $150 for a battery, $150 for a fuel gauge regulator, $320 to replace the THROTTLE BODY which I read on this forum. I have been driving it everywhere for 2 weeks now with no problems. Oh, the other $700 was for new tires which I could commit to buying because my truck is finally working. I want to thank all of you who suggested the throttle body replacement fix. I still had people telling me a tune-up, a coil replacement, etc would solve this problem. They were wrong and you were right.

100100100

On mine i changed the pedal that didnt fix the problem i exchanged batteries for a new one.no fix
Until i noticed a plu where the battery is all the way passed the fuse bax theres this thing bolted to the frame.theres 2 plugs one was unplugged.plugged it in its been good for 2 days so far.

bennc

2006 Yukon Denali here. Car is showing messages of "Reduced engine power", "Stability System Disabled", and TC (Stabilitrak) light is on as well as service engine. Car idles poorly and feels unstable. Happened only when I turned it on and turning off and on doesn't reset it. Any updates on this issue ? From the posts I've read seems like 4-5 possible reasons.

karenwilliams

I have a 2008 yukon denali and getting service stability track,traction control off and engine power reduced.   You can wiggle wires most times and get vehicle running again. Today had to just sit on side of road each time for about 10 mins. And it would start back working.  Had to do this 5 times on our short drive from town today.  As far as I can tell....this has been going on with gmc since 2003.   It is CRAZY that GMC hasn't come out with a recall . Any help would be appreciated .  Oh also get the warning to charge battery system all the time too.

ChipChester

Have a 2003 Suburban 2500 which recently developed the P1516 problem. Have addressed almost all the grounds in the engine bay (including the one on the alternator bracket that was grounded to a powder-coated part. Hmmm...) Have one more to go on the back of the engine/passenger side. Still need to bug out the TPS wiring.

I have a Tech 2 analyzer, and did capture one REP event. Still looking over the data, and trying to determine what the tolerance is for the redundant control circuits to "agree".

The Tech 2 actually retains data for a few points in time during the event. At the time of the event, the Accelerator Pedal was calling for 30%, the TP Desired Angle was 27%, and the TP Indicated Angle was 32%. So some big differences.

More detailed info is available in other screens around the event. One data point in the instant after the code was thrown:

Throttle Position Desired Angle was 12%
Throttle Position Indicated Angle was 17%

So I would agree that a 5% difference is enough to throw the code. The accelerator pedal was off at that time, because I let up (0% on each) -- with the voltage at the pot of .55V on sensor 1, and .57V on sensor 2. These pretty consistently track .02 to .04 V off from each other, which I think is probably OK for an analog voltage in a car that's 16 years old. (but only 118,000 miles.)

So the Throttle Body was either sticking open, not closing fast enough, or there was a wiring fault that reared its head at an inopportune time. Removed the TB and cleaned it thoroughly, replaced. Did the 'tug test' gently on wiring at the TB connector. It ran better for the next day or two when it was cold and dry, but once the rains returned, we're back to a couple resets per trip. (I have a reader plugged in all the time, so I can do it while driving -- but it's still not fun.)

Various internet browsings have targeted the cause to be wiring, not sensor related. I'm going down the path of making sure all my wiring is good before replacing the sensors.

I should note here that my other 'car' is a 50+ year old British sports car, that is no stranger to electrical gremlins. Experience has shown that most sudden onsets of weird problems in normally-unrelated systems boil down to bad grounds. Grounds are usually designed 'geographically', grounding whatever circuit is nearby, rather than being functionally segregated. (Audio systems are the usual exception to this.) On more modern cars, the attempt seems to be to carry grounds to the device, rather than rely on local grounds. This is good and bad -- few things are more robust than the frame of the vehicle, but making a rust-free connection to the frame can be an issue. (Which is the issue I think I have.) Carrying ground wires in the harness is the other approach, but then you're running grounds thru contacts in a connector, which increases possibility of failure.

I'm going to clean-up the frame and tighten grounds at the point below the driver's door hinges (based on internet remarks) and attend to the back-of-engine grounds too. Then I'll begin the hunt (on the internet) for the location of other ground points outside of the engine bay. We'll see how that goes.

I'm toying with the (ill-advised) idea of eliminating the redundancy of the position sensor system, and hard-wiring the wipers of each pot together (temporarily). The redundancy exists to prevent a bad potentiometer from giving you full- or no-throttle. But connecting them together would result in only slightly more open or closed throttle positons, not full-on or full-off. You may be left with fast idle, or have to 'give it more gas', but you'd have more than 10% power. Not a long-term solution of course, but it would let me wait until it's warmer than -6 or so to work on it...

Chadwrench

Okay so as for my 07 tahoe stalling out and the message center displaying reduced power and stabilitrak service and oil pressure low along with the sputtering like alot of you on here have discussed. Turns out it's not the sending unit, throttle body, fuel pump, grounds, or the ignition. Rather it was what controls all of the above. The ECU. Which explains why everything went on the fritz all of a sudden. Just thought I'd include the one thing that I didn't see anyone else mention throughout the thread. Hope this can help someone else.

Jacobl1978

Hi all . I had this problem on my 2003 Yukon so I searched and found this sight. My Yukon has set for say 2-3 weeks . When I started it battery was dead . Went to hook up a battery charger but an alligator clip was broke so I loosened the ground to hook up behind that post. It did start with a jump but low engine power light came on and hardly any power. Read post of loose ground. Unscrewed the ground reconnected and started without charger. Message gone but engine light is on. Letting it sit now with engine revved up will see what happens. But I do have power more power now .

Tykeith04denali

FIXED AND SOLVED THANKS TO YOU GUYS . my problem was the reduced engine power had the throttle body codes HOWEVER everything to do with my actual throttle body was okay I checked grounds they were good shook the harness and no matter what I did couldn’t even get it to come off for a second ! After buying a used throttle body and going to install it I had to unplug the plug out of the throttle body only to see it did the same thing . DONT BE FOOLED BY THE HARNESS IT MAY LOOK OKAY BUT MAY NOT BE I have checked this harness and shook it with nothing I got a needle nose pliers and gently tugged on all the wires on the plugs to check for loose wires low and behold the blue one bottum left corner slipped right out . I shoved a new wire in there and connected it and WOLAH engine power reduced is gone !!!

David_Zanovitch

I've had the sudden power loss problem sporadically for the last 4 yrs on my 03 Denali. FINALLY FIGURED IT OUT. Under the engine plastic cover found a leak in the Genuine GM Parts 17113556 Fuel Pressure Regulator Vacuum Tube. Got it next day from Amazon and my 4 yr headache is gone!!