Reduced Engine Power Warning And Check Engine Light

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94 Comments on "Reduced Engine Power Warning And Check Engine Light"

Chris Smith

2017 Sierra 1 month old has this issue already! Sure my warranty will cover it but who wants a brand new truck with problems


I have a serious problem .. I over fuled my car so I had to change my engine the person who changed my engine for what ever reason did not change the airloom cable it said ‘ engine power is reduced ‘ and I was not able to drive over 30 mph .. Now the air loom cable is swapped over and codes have been rested and the new people I have taken it to have said their not sure why it’s still there . The car is driving 70-80 mph now so very strange anyone have any ideas ? I have a Vauxhall corsa 1.2 15 plate .


Have you taken the throttle body apart for any reason?? When putting in the t.p.s. throttle position sensor in, it has to be put in just right or basically u lite the fuse when turning on car.. vvvvvvvrrrrooooooooooooooommm! Or maybe just put shit back to where they came from?? And then do the reset….. that way everything is working the way it’s supposed to whend it starts fresh. ;) sounds to me your doing it all wrong boy.


I have an 08 chevy Silverado 2500 hd 4×4. last night I was driving it amd all of a sudden it said engine power reduced and wouldn’t go get fast if i tried to push the gas down to far my rpms would go up to 5 can anyone give me a few ideas on what it could be


took my 2008 silverado to chevy dealer with 104000 mles on it . the dealer said G M had a recall on the T B I and it was fixed at no cost to me. They also gave me a car to drive while mine was being repaired.


I have a 2004 Chevy Silverado 4.3 1500 when I’m going up a steep hill my check engine light flashes 2 times and I tend to lose horsepower I replace a Cadillac converter already twice and my transmission is rebuilt what could be the problem


i had the same problem my reduced engine power comes on so i couldnt do more than 15 miles per hour i pull over turn car off for 5 minutes turn back on no problem it would run until happen again it was my TPS i changed it 70 dollar part took 5 minutes no problem since then

could the use of E85 cause “reduced engine power warning and check engine light?


I had no more problems

Hello guys I do know that this is an old post but I do hope that my comment helps at least one person because I know how stressful this situation is. I have a 2002 GMC Envoy since I’ve had it for about a year now I’ve been having the issue with the reduced engine power light & while that light comes on the service engine soon light also comes on but the thing is mine only did this when it was cold or chilli outside about 60 & below it would stall & those lights would pop on and it’ll start shaking a little bit. I would let my car warm up for about an hour on cold days that was my temporary fix for the day. Over the year I took my car to a total of 5 different shops and no one knew what to do everyone was so confused expect the last shop I took it do they told me it was definitely the throttle body so I replaced the throttle body $450 (after tax) I get my car back the same day it worked fine but it was also warm outside so I expected that then at night when it got a little chilli I started my car to see if I would have the same issue & low & behold those lights popped on &Amy car started acting up again. So the same shop came and picked up my car the following morning to see what the issue might be they called me back shortly after & informed me that I needed a new computer( PCM)in my vehicle & it had went bad. I thought that this car was just a money Pitt I was so frustrated but the computer cost $153 after tax… Read more »

Have you had any more problems?


Had very similar issues with my 2008 gmc savana 1500 like everyone else. I’ve spent hundreds if not thousands on repair at various autoshops in which I was slowly loosing faith in GMC/ GM. My issue was resolved with my engine power reduced problem and turns out, the vehicle iddle just needed readjusting. Not sure if that will be everyone’s fix, but it’s worth looking into. Really hope it helps.


I have a 2003 4×4 LT Chevy Tahoe with over 240k miles. Over the passed 3 years, I’d had an issue with the Reduced Power Mode coming on, shutting down my Tahoe and forcing me to pull over, turn it off, wait and the fire it back up. Sometimes it will kick it out of the Power Reduced Mode, but the engine light will stay on. Other times it won’t work, I’ll have to turn it off and wait longer. I’ve replaced the following

Fuel pump
Fuel filter
Gas cap
Intake manifold
Throttle body
Pig harness

All seemed to work but after a while, the same issue came back. I’ve read multible forums looking for the answer, no shop has helped, no 1 forum has helped. Has anyone replaced all the here parts and still had the issue? Has anyone found the caused and fix of this issue? Truck still runs great as long as the Reduced Power Mode doesn’t come on. Please help!

I read Ken’s response to the daytime vs nighttime issue. My truck throws into the Reduced Power Mode day and night, freeway or town traffic, while driving or at a stoplight, while driving or right when I turn it in. There is no rym or reason as to the time of day or volts being pulled from the battery. Ie, lights, stereo, etc.


Have you bought a new battery


I have. I’ve purchased 2 batteries since this problem arose.



Have you tryed replacing the camshaft sensor


I have not! Nor have I replaced the knock sensor. I was told I should have when I replaced the intake manifold. (Had I been given the option from the shop at that time, I would have.) have you seen this problem corrected by replacing the camshaft sensor? Cost and can it be done by me, or is it a shop recommended item?


Hi Dean! I have a 2004 4×4 Z71 Tahoe with right at 175k miles and am having the exact same issue with no rhyme nor reason apparently bc I can’t seem to find any consistencies for when this occurs either?! We’ve taken it to get looked at once so far where they ran diagnostics and drove it a little bit, and said it was perfectly fine. After finding this article and reading all you have replaced and have been through with this issue, I can only imagine how frustrated you must be! Just so happens I talked about wanting to sell a week prior to this issue starting, and it’s happened now about 10times within the last 3 weeks! But today was actually the first time I had to actually leave it and get someone to come pick me up. It started up just fine, but as soon as I would go into reverse to back out it would say ‘Reducing engine power’…and you know the rest! I tried several times and then waited a good 30mins before I tried again when my dad came to pick me up and/or try to drive it himself to see what has been going on. Did the exact same thing immediately, so I’m at least glad he got to finally see what is going on. Im also grateful I read this so that we now know that replacing the parts you listed above aren’t fixing or helping the issue! Any updates on figuring out what the problem is? Hope you get it figured out!


i real don’t think knock sensor will help. or the cam or crank sensor. there is a problem in the . the foot pedal or the throttle body . if its the cam or crank sensor it will kill the motor. the knock sensor will just turn on the check engine light on. and replacing the battery? it’s main job is to store power to start the motor. just have your local auto store check the batter if its good. your good. !!
now the throttle body and the foot pedal. they are both electronic sensor with sensors tell sensore to do there job . of one of the those electronic sensors get a bad connection ” Check Engine” light.. now let see if someone is will to help us out on how to check out those things thing. “electronically controlled throttles” ” foot pedal or throttle body”

2003 gmc 2500 hd, 6.0 auto 4×4. Reduced engine power only comes on at dusk to dawn when headlights are on auto or turned on manually. I pulled the two relays for high and low beam lights and it runs fine with no reduced power message. It will also happen(reduced power) when air conditioner is turned on. Seems to this old school mechanic that I have maybe several bad grounds, any thoughts? I can drive all day long without air turned on and headlight relays in place with headlights in auto mode, but not on, but when sun goes down and lights come on it goes to reduced engine power. Also both the drivers side high and low beam headlights are dimmer than passenger side, also maybe bad ground. Help!!


I have the exact same issue ken. Like identical on my 04. If you find anything out plz email me your solution.


Same exact problem. Going crazy tracing wires!! Did you find a fix?


Never found one. Pulled my relays for ac and headlights. Wired my heaflights to a switch… what a pain.. prolly.something.simple

gat a 2008 dodge magnum running 60 mph and let off gas my car jerks and the check engine light is on what is the problem

Israel chavez

I hAve a 2014 gmc Sierra and da reduced engine power and check engine light are on what should I do

I have a 2015 Equinox & the check engine light & reduced engine capacity message came up….I am soo upset! Going to a mechanic today….


I have a 2008 Suzuki xl7. We replace the throttle body but the idle is not right. Also got the map sensor but was given a different part. What else can I do


have a 2000 Tahoe reduce engine power, traction assist, service engine soon lights come on obd2 code 1221,how do I resolve problem ?


I have 2006 Chevy Silverado 1500 with hid headlights and what not and the other day it kept saying reduced engine power when I switch from my bright lights to my low beam lights which has the hids in them


I have a 2008 impala and the. Engine read reduce speed and the traction light came on and said fix traction.where I got the car from said it was a censor they changed it it came back on I took it to a shop to get it read they told me it was something with. A modual is that bad


I have a 2004 trailblazer and when im driving the check engine light stays on and I can get a little ways Nd reduced engine power light comes on and it starts sputtering and I lose power! Then it usually takes about an hr then it cranks up and I get just a little ways and does it all over again! Ive chAnged the smog pump but it didnt work. Please HELP ive only had it a couple months


SAME problems with 2003 Trailblazer…
Been told to replace the ECM-Electronic Computer Module.
Will be doing within a week or so…
Will try to give you the results or answer as to whether or not it fixes the problems


What was the problem


Did that work


I have a 08 yukon i change the throttle body but now the truck is really accelerated. What can be the cause of this problem


i’ve heard that when you replace the throttle body the ecm has to be calibrated and sometimes new software added. I understand it a dealer job. info gotten for you tube post.


You possibly could have a vacuum leak, but more likely you need to have the minimum idle relearned. You can try to run the truck for 10 minutes in gear with foot on brake, shut it off for 1 minute, then do it again,. If not, you will need to have it reset with a computer san tool.


I already change throttle body and acelerator sensor and module between those two and still reduce engine power


Check wire harness also check air filter. Dirty air filter can give throttle body wrong reading.

Thank you for the info. Engine light, Traction control off light, and ‘engine power reduced’ message on on dash of my 2007 Chevy Malibu. Car starts but acceleration is slow and dies every time you hit the brake. Sounds like you’ve narrowed down my problem for me. WAY to complicated for no particular reason. Give me a steel cable, or better yet a steel rod linkage any day. Cheaper, simpler, more reliable. It’s a Family Sedan, not a performance vehicle I REALLY don’t care if the response ins’t ‘instant’ This Chevy Malibu has proved itself quite the lemon over and over again. NOT a good car.


i have a 2005 saturn vue engine light comes on then engine light will flash on and off. looses power gets load and has a miss to it when stopped at light please help


I have a 2007 silverado and I’m having trouble finding my tac module. I replaced the pedal sensor and the tps sensor and still having the problem. When the truck is cooled down it works fine but after about 15 minutes it warms up and the accelerator stops working.I also cleaned the throttle body and intake but my main problem is finding my tac module


I have a 2001 GMC Yukon
The reduced engine power light came on
.Low coolant light keep coming on.But ,found out the water pump.has a hole in it.Had a problem with the battery.Could the battery be the problem

My 2003 Saturn Vue, I have a broken exhaust pipe…my reduced power light came on & engine light…idled home, shut it off and I was able to drive to my drivewqay. There it sits, could exhaust be the problem?


I had this same problem with my 2008. GMC Saturn Vue. I pulled over added gas then turned off truck. And reset the engine by turning the ignition on but not starting the vehicle.. pumping gas pedal twice. And it started and was driving back to normal.


I want to thank you so much for your post. I have a GMC 2003 Hummer H2
I read your post. I had reduced engine power Turn ignition on but not start , pump gas peddle twice crank up Hummer full rmp again. Thank you. You helped me very much. This worked. I tried other things I read other places. Though you post wins the Hooraa yes from me


Erica, Thanks for posting this information. It just happened to us. We are going along with cruise on 70 and engine goes into failsafe mode. Your suggestions worked and we are back on the road under full power. Check engine light is on and will have this looked at early next week.

Carlos velez

I have a chevy trail blazier the check engine light comes on with reduce engine power it wont run it feels like it wants to but it wont run


I have a 98 honda civic i changed throttel body an throttel sinser an still haven the vu vu vu vu wile n park an driveing it to its a automatic an fils like im driving a tspeed i fille like its changin gers but idts cuz it drops speed from 35 too 20 an its scary having this problums with bbys n the car some one help

Tim Gonzales

I am an ASE master certified auto technician I currently have a 2004 Silverado 2500 hd 6.0 L with a reduced engine power light the tech that worked on the truck before me replaced the harness going to the throttle body reprogramed the ecm and replaced thee tac module he also said that the check engine light was coming for a no communication code to the tac module so I hooked a lab scope and check for bus data confirmation it was talking to the pcm so are issue is intermentent I also noticed while scoping the 5 volt ref going to internal tps sensors in the throttle body I found that one 5 volt ref was being pulled to ground I was trying to find a pin out voltage test specifications but did not .so I will have to reverse engineer the system and continue diagnostics on the tac module I noticed in the wiring diagram that the cruise control module ties into the tac module when problem ocuurs I wil unplug cruise control module to see if that module was pulling down my tac module causing my bus data lines to freak out. will continue when I find fix.


Have you found a fix

rose.hardin143 @gmail. Com

I have a 2006 four wheel drive trailblazer it ran 13 codes it says pedal position at sensor 1-2 failed app sensor – control module throttle position- air injection system pressure sensor- air injection system shut off valve stuck- air injection system pump stuck on- engine coolant temperature sensor- oxygen sensor effective- throttle position sensor- short sensor on 5 volt circuit- air injection system pump stuck on filter air control relay- failure fuel level sending unit- engine control computer it says call Cardone at 1 888-280-8324 for flash I have the same thing everybody outside loss of power come to the stop sign it shakes and rumbles sometimes it gets going after a while and then sometimes it just slows down and go anywhere and sometimes the light on the dashboard go off and it still runs with no power an it idles quite a bit what do I do what does all this mean I can’t afford anything I can only buy one parts for each month after bill’s are paid if I’m lucky Thank you

Tim in Gilroy

Changed pedals sensors, throttle body is new plus upper and lower wiring harness. I’m still getting engine power reduction code. Found out engine mount was broken in half with no rubber left at all.
Can this cause engine power reduction?
2006 Chevy HD 2500….Thanks!


Hi Tim in gilroy I’m having the same issue did u figure out the problem?

Yes, engine mount broken was pulling on wires causing the problem.


I went to a mechanic because my engine light came on. The mechanic told me it was the solenoid in transmission , so I told them to repair it . 900.00. The light was still on. Then he told me it was the brake light switch. Replaced that ,light still on. Can so eonehe me

Mike Perrot

I have a 2005 Saturn Vue SUV 2.2. 4 Cyl.and the Excelerator does not work.I can start the vehicle but when I push the Excelerator in the RPMs don’t go up.I noticed that the Excelerator pedal is do I diagnose this problem?


Hello everyone my name is Chris I have a 2006 hummer H2 ok this is what happen gas light was on got gas then got on freeway drove about 7 miles then check light and reduce engine power on dash I could not get any acceleration put hazard lights on got over to emergency lane asap turn motor off for 5mins then started engine dash still says reduce engine power put in drive max speed 20 to 25 mph any ideas


Wiring to throttle


I have a 2003 Tahoe with service engine light and reduced engine power. I’ve had two tps and two accelerator position sensors, also a throttle body and a pcm replaced and still have the same problem. The code comes as tps correlation or misconfiguration and pedal accelerator sensor. Chevy still doesn’t know what’s wrong with it and my funds are now extinct. Also ground wires changed. My car runs perfect until code comes on. Can anyone help me PLEASE..


I’m having the same problem with 2003 Tahoe..


Hi I’m having the same problem did you happen to find the issue?


Hello!!! I have a 2005 buick lacrosse 3.8 .. i was driving the other day in the rain went thru a few deep puddles of water.. later on that night my engine light comes on then the car died and said reduduced engine speed. Its started back up then dies again this time i need a jump that this. I jump the then make it like a mile samething it dies.. so the next day i reset the computer the engine light goes off and it rides fine till later that day .. engine light come back on and reduduced engine speed then it dies .. now it wont start!!!! Could it be possible the crankshaft sensor got wet or maybe the wires? What you think?? Its turning over and getting fuel but wont start… please help


my buick 2005 is doing same thing…my mechanic & dealer don’t know what’s wrong with it. Help!????


Our Chevy dually has the reduced engine power on… and it’s constantly coming on and losing power to where the truck goes 10-20 MPH… what is the problem?

Kristopher Harms

2002 GMC Envoy

Check Engine – Constant

Reduced Engine Power w/ Throttle Restraint – Spontanious

Throttle returns after engine restart.

During throttle restraint vehicle does not shift into overdrive but will easily do 3k Rpm in 4th gear.

Replace throttle body and possibly wiring?

I have a 2004 Chevrolet Trailblazer LS, on my way home the Reduce Engine Power light came on,what does this mean and is this expensive to repair?

Julian bond

I just put a motor in my 2004 Chevy Tahoe z71 I can’t accelerate and my reduce engine power comes on I’ve change the throttle sensor as well as the throttle if any one out there that can help me call 3124345530 will pay

bondj133@att. net Julian bond

I just put a motor into my 2004 Chevy Tahoe z71 the problem I’m having is this reduce engine power I’ve change the throttle sensor the throtter and its still not letting me accelerate and the reduce engine is still on if any body can fix this problem for me please contact me I will pay # 312 434 5530 thank you


2005 chev silverado reduced engine light comes on … usually hot weather..hasnt done it for awhile running soon as weather warmed up it started doing it again…


I would need to know if any codes were in the computer. If not, sounds like you have a wiring problem.


I have a 2004 Gmc envoy I replace the throttle body with a new one that cost me $400 ..then I got a gas petal dat was $100 more and my reduce engine light came bk on…took it to get a diagnosis test any nothing come up….what is my problem


I would need to know if any codes were in the computer. If not, sounds like you have a wiring problem


my yukon had a code of 1153


My 05 GMC truck is doing the same thing, I’ve replaced all the same parts and also replaced the battery. What kind of wiring issues should I be looking for?


I would like to know do you know what type of wiring problems you were experiencing. I’m having same problem


I have a 03 Chevy Silverado z71, I had my reduced engine power come on about a month ago when I started my truck, after shutting the truck off a few times and restarting it it went away and drove just fine. Now I warmed my truck up and when I was ready to go the truck shut off and I have absolutely no power, I ended up getting power back doing nothing to the truck but that lasted like a week, now I have no power and I can’t figure out where the bad connection is or is the issue related to the reduced engine power. Idk, any help with be great.


I have a 2006 Saturn relay 2 and recently the engine light comes on and a message that say reduce engine speed and the van slows down. What causes this?


There can be many reasons why you lose power in your Saturn. The first step is to have the computer scanned for codes.


I have 2003 trailblazers an my reduce engine light come on an if I pull over an shut the truck off for about 10 to 15 teen second an start it back up the light goes off for a while. An the check engine light is staying on now


I have a 04 chevy silverado z71 thought I carefully rinsed my engine now when I drive just a little ways my reduced engine power comes on and the truck accelerates on it’s own until I shut it off is this part of the throttle body system as well?


Yes, it could be. Water may have gotten into the throttle wiring connector.

Jorge Ramirez

i also have a 2004 gmc sierra 2500 hd and it keeps telling me to reduce engine power i turn it off for about 15 sec and the code goes away for few hours but it does have a throttle code going on.

Yes, sounds like you need to have the throttle body replaced and the idle learn reset. This is a common problem.

Linton Dixo

I’m having the problem reduced engine power every time the light comes on my engine goes into a stall to where it doesn’t want to pick up speed


I have a 2006 GMC Canyon 4 cylinder engine I changed out the fuel pump once to turn on the truck the engine reduce light came on on the dash and the truck does not have power. I pushed the gas pedal and nothing what else can my truck have it never had a problem til I changed the fuel pump.


It depends on what codes are stored in the computer. Sounds like your truck has a problem in the electronic throttle system. Maybe a bad accelerator position sensor which is part of the gas pedal.


My 2005 Chevy Equinox while we were driving started showing the battery light, slowly after a lot off more warning lights came. Then my accelerator didn’t work,,then it shut-off. My battery was dead, it was replace since it had warranty, i had the alternator rebuild. Now my car starts but the accelerator moves inside the cabin, but it doesn’t due nothing in the engine.


You need ti get the codes cleared from the computer and check the Maxi-Fuse under the hood. See this link…

Robert De Leon

I just bought 2006 4.8 Siverado and wash the engine yesterday then the Reduced engine light came on, after 15 minutes of driving and restarting then engine it went away.
Should I worry or was the cause for washing the engine?
Thanks Robert De Leon

Ray Thornton

I have a 2003p1125 GMC Yukon xl with about 143000 miles. We are getting a p1125 code and having reduced engine power. We have replaced the throttle body, app sensor, and wiring to throttle body, but code still comes up and reduced engine power. What else can we do?


There is another part on your vehicle which controls the functions of the throttle body and communicates with the PCM accordingly. That part is called the TAC module (Throttle Actuator Control). It is located on the firewall. That is what most likely needs to be replaced on your vehicle. It does not require any programming, so it is a part you can replace yourself.


My s-10 pulls while accelerating..changed fuel filter but still does it. what else could it be?


A fuel filter would have nothing to do with the truck pulling to one side or the other. You either have a front suspension part gone bad, or a broken motor mount. Put the truck in drive with your foot firmly on the brake pedal and give it some gas. Have someone look at the engine to see if it is moving excessively.