2004 GMC YUKON P0120 P0220 P1516 REDUCED ENGINE POWER - DIAG AND EASY FIX

[@panfishin-fool8057]

Dude You are Heaven Sent because I just purchased the 2004 Denali XL yesterday as is with no warranty I knew I was taking a big chance but my back was up against the wall considering everything is so expensive at the moment.The truck drove home fairly decent yesterday except shifting at 2500rpm. This morning on my way to take my daughter to school I had this problem and panicked and in them stumbled across your video so I pop the hood and that exact wire was unplugged🤦🏾‍♂️ I can be honest and say that I was literally going to cry thinking I completely just threw three grand away

[@panfishin-fool8057]

There's a misfire issue also a slight ticking going on so im wondering if you can point me on the right direction also let me know what other issues I'll be facing. The truck is super clean inside and out and I'd like to know why someone would want to get rid of a almost-perfect truck. I also believe that someone rigged the odometer because it's reading 55 881 which is very hard to believe so if you know how I can find out the exact mileage that would be very much appreciated blessings to you bro

[@DallasAutoDiag]

Im happy that it helped

[@panfishin-fool8057]

@@DallasAutoDiag I am more than grateful. God knows this is a evil world so he put people like you to come forth and be honest and help out other good people in need

[@Im_workin_on_it]

​​@@panfishin-fool8057same issues any luck finding out what was wrong

[@that70slifetimetravel]

Thanks! I now have another idea on what to check! This thing is driving me crazy! The engine design "experts" at General Motors need taken to the shed for a severe administration for this one. I've been trying to fix my 2004 GMC Sierra for about two months now. I have a handheld diagnostic scan tool called an ANCEL AD530 (good machine). It continually throws the exact same three codes: PO120, PO220, P1516. I've replaced all of the grounding wires I've found on the hundreds of KZbin videos I've watched on this problem. I've replaced the Throttle Body (new), the Throttle Position Sensor (new), the Accelerator Sensor & Pedal Assembly (new). I thought I had it fixed once this past week, but it said, "No you don't!". Running down a wiring harness is above my pay grade, but I can definitely do some visual inspecting. I'd bet a lot of money that the GMC/Chevy owners who haven't had this problem are in the severe minority. Videos like this are appreciated BIG TIME! I'm glad you posted it! And the comments from viewers help, too- even if it's just to commiserate!

[@DallasAutoDiag]

Hopefully you solve the issue soon.

[@that70slifetimetravel]

@@DallasAutoDiag Thank you! I appreciate that. It's been starting and running fine the last few days. Fingers crossed! People like you who take the time to post these videos to help people out are the best! Keep on keeping on!

[@markiemark_bag6037]

@@that70slifetimetravel so what u do to fix it

[@that70slifetimetravel]

@@markiemark_bag6037 I hate to tell you that I still haven't fixed it. It's been on the back burner lately because, in addition to the truck, we have an SUV (Chevy) and a minivan (Pontiac) that aren't working now. Out of three vehicles, we have ZERO running! Needless to say, I'm not terribly happy with General Motors these days. I actually started working on the truck again, earlier this morning. I'll report back to this thread as soon as I figure it out. I'm not a mechanic at all, but I'm refusing to take it to a dealership and pay them to fix the problem they caused.

[@that70slifetimetravel]

​@EyesToSeeTV I'm glad you asked because I couldn't remember where I had commented about this problem. Yes, it's solved, but I still can't believe what it was- the simplest of solutions: I replaced the battery with a new one and have never had the problem since then. I had noticed it was starting to "drag" (even acting like it hesitated for a split-second) during cranking. I actually though it was the starter, initially, and decided to just go ahead and replace the battery. I got the highest CA / CCA I could find and put it in. It cranks like a beast now (we're having single digit degree mornings) and "Reduced Engine Power" message has never returned since then!

[@condor5635]

I had success with changing the actual accelerator pedal position sensor. I had already changed the throttle body sensor, and re-checked all of the grounds. I was getting a P120 code. Switching out the sensor is very easy and it solved my reduced engine power error.

[@louannwatt4447]

Thanks. The lesson here is that you followed procedure and didn’t assume. Good job.

[@abramemmitt9103]

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[@westonzayd737]

@Abram Emmitt yea, I've been using flixzone for months myself :)

[@marvinnova1553]

@Abram Emmitt Yea, I have been using flixzone for since december myself :D

[@leeforrest9661]

@Abram Emmitt Yup, have been watching on Flixzone for years myself :D

[@gerardoreveles3156]

Thanks for the one make this video same thing was wrong with this 05 chevrolet tahoe, you save my life 🎉

[@DallasAutoDiag]

glad it helped

[@aramizgil986]

mine was the pigtail Connector was bad , but I also replaced a OEM TB and Mass Flow sensor aswell. Running like brand new again .

[@DallasAutoDiag]

Glad it's fixed

[@carlosgutierrez1918]

I've been having the reduced engine problems for 5 years lol.. still takes me to Tahoe and back. Just have to pull over turn off and on and Rev a little...lol..comes and goes for months then does it for a week lol

[@SydWaters1776]

I have the same issue in my '04 tahoe 5.3.. It's not a fix but if you go into reduced power.. Pull over.. Shut off the engine. Disconnect the negative battery terminal.. Wait 15-30 then reconnect. Start the truck. It should be running normal again. Also a trick so it doesn't get kicked into reduced power is to be a little aggressive from a stop and up to the speed limit then from there hit the throttle and let off. Don't keep the throttle in the same position for too long. Ex.. If speed limit is 45 mph get going to around 50 mph then let off the gas and coast for a second then hit the gas again keeping it between 45 and 50 mph. Don't try to use cruise control. I've tried everything to fix my tahoe even put it in the shop. Still the same issue but I've done well with the above advice for over 3 years now.

[@brandonsmith5692]

I bet the problem came back

[@drebaker3074]

For Sure!!!

[@bigcraigz]

I have a 03 Yukon denali. Same problem except all my dash lights come on right as the reduced engine light comes on. Code is p1516 I put 4 gauge grounds everywhere the truck has grounds and replaced the ground behind the back of engine block on passenger side under drivers door on frame cleaned and inspected all plugs to throttle body still same problem I was also getting a TAC code sometimes when it happens but absolutely can not figure it out. Please any information you could help with would be greatly appreciated. I paid almost 10 thousand for the truck less then 2 years ago and cant even drive it now.

[@DallasAutoDiag]

What city you're in?

[@bigcraigz]

@@DallasAutoDiag Cleveland Ohio. Still have the problem. Codes are p01516 p0442 and p0446. Any ideas would be greatly appreciated

[@DallasAutoDiag]

@@bigcraigz Honestly this is not a dyi code. I would suggest you to take it to a good local mechanic shop.

[@Teriaki123]

Having the same codes p1516 p0120 and p2135 replaced the throttle body, tb connector,pcm, accelerator pedal assembly. Was working fine for 4 months no codes, no limp mode. Now I erase the codes and works fine for a week then limp mode again where do you think i should look next?

[@DallasAutoDiag]

Check to see if pcm has latest software version on it.

[@Teriaki123]

Ok i will look into it. It’s on a 2005 gmc sierra 1500HD 6.0

[@dvr6o367]

Would you happen to know what would cause code p1514 I replaced the MAF and it’s wiring harness and the TAC and throttle body and the truck will still go reduced power

[@crystalaranda859]

Thanks you helped me God bless

[@YN_Chiefmeasy24]

I’ve changed pigtail , throttle body assembly , Whole TAC system , pedal even grounds still same

[@DallasAutoDiag]

sorry for your trouble

[@gmccuh1413]

P0120 and p2135 i have and i have a misfire everytime i go full throttle car hits 2500 rpm misfired goes to limp mode

[@panteraklan681]

Sir. I hope u can put to the right direction, i got the same problem on my 2004 4.8 silverado, i change tb, tb plug, whole pedal, tac module, i check power and ground to tac module, i check my grounds around the engine and still with this problem. Did u have any advice pr experience with it?

[@DallasAutoDiag]

I think its time to check if all inputs and outputs are good at the pcm, if they are then it might be your pcm. don't take my words without checking.

[@ALFREDOCHANGOMORENO]

Check all the vacuum leak hose I replaced as well all the parts in the end it was a crack hose

[@Quinceyb4]

@@ALFREDOCHANGOMORENO What hose was it

[@chipdip6577]

What state are you in can I please pay you and fly you also to fix me truck please man !

[@Chevydude35]

Update to my issue, the bolt a bracket that holds the two halfs of the steering shaft together snatch out one of the spark plug wires, I was able to put it back on but I had to zip tie the wire away from the shaft.

[@rolandobarral5333]

I changed the pedal sensor and the throttle body, I still get engine power reduction and I used 2 different scanners and I don’t get an option for a relearn, I used a Tech 2 and a snapon Modus and there is no throttle idle relearn option!

[@ALFREDOCHANGOMORENO]

@@rolandobarral5333 i am in the exactly same thing Did you fix the problem

[@TheyCallMeGator]

@@ALFREDOCHANGOMORENO did you figure it out?

[@TheyCallMeGator]

@@rolandobarral5333 did you ever figure it out?

[@ALFREDOCHANGOMORENO]

Yes, I did just check first the relays In my case the a/c relay was blown out they share the same ground Check the relays first and save money 💰

[@sahle_koko1614]

can someone help help me my gmc suburben 2001 has rouph rpm and when i try to hit the gas pedal it wont go up than 3500 rpm and its shaking some time when i turn the ac on it get worse like the car can not keep runing with ac on or when i turn the steering it died for no reason please help me before i burn my car i hate it

[@rolandobarral5333]

I have a 2003 Yukon Denali, and I had gotten some codes , p1516,po220,P0120, P135 . I checked the harness and checked the ground on the truck , looked for corroded wires and harnesses and all seems good!!I tried 2 different scanners, I tried the Tech2 and snapon modus and I don’t see a throttle or idle relearn option and I’m just stuck on a power decrease mode and cannot clear codes! The pedal position sensor I switched for a new one and the throttle body also I replaced it and still stuck on that mode! I tried manual ways to reset and yet the same issue I cannot get it to relearn! I tried driving it to get maybe for it to gain speed but it doesn’t pass 15 mlp

[@DallasAutoDiag]

Forget everything you did and start basic. First let's check values at the throttle body connector. Check with scope if available, if not a voltmeter is fine. Compare to a known good. I'm sure you can find some in the we'd, if not let me know i could share some values with you.

[@paulbrown6436]

Everything you did I did but the reduced power will still come back on once the engine is warmed all the way up

[@DallasAutoDiag]

Is there any other code? Whats the history o lf the car? Were there any parts replaced?

[@tranix303sanchez7]

I have a 06 Yukon denali xl 6.0 I have changed the pedal the harness the throttle body and sensor took it to a elecation and still getting the rudeced enigne for over a year and now getting p0120,p2135,p1516 took it to mechanic n they can't figure it out. Any ideas anything that has to do with the throttle system is all switched brand new.

[@ryanlopez4371]

Any update?

[@ALFREDOCHANGOMORENO]

Change the ac relay

[@averageryze6465]

@@ALFREDOCHANGOMORENO would it actually help ?

[@ALFREDOCHANGOMORENO]

Yes just check them you will see the relay blown oit

[@averageryze6465]

@@ALFREDOCHANGOMORENO how can this be a problem just curious

[@Chevydude35]

I have these three codes on my GMC plus a P0300 code, now would the P0300 code cause the other three codes?????

[@DallasAutoDiag]

No its the other way around. The 3 codes cause the p0300 code. Basically it's for a misfire event you had.

[@kenyamariejohnson7126]

I have this with my 2003 gmc yukon1500.... Should I just change the whole throttle?

[@DallasAutoDiag]

No, try to inspect the harness first.

[@timramirez4121]

It will come back, it probably a grounding issue, losing communication with tps.

[@DanielRodriguez-oq8xh]

Can someone please help me im going through the same ish,changed almost everything and still reduce Engine Power!!! HELP ME???

[@DallasAutoDiag]

Let's start with scanning the car and see what codes does it have

[@brandonsmith5692]

GL man! Mine goes away comes back. My code now is p1516. Already changed tps no no help. I can drive it but it always comes back

[@nereidaolalde7851]

@@brandonsmith5692 Same Dam Problem 3rd time doing this it did it today now back to the shop it goes 🤯 I hate it

[@gillv6330]

I had the same problem I change the throttle body, map sensor and maf sensor. It didn't go away until I put in a new alternator

[@gillv6330]

The alternator could be messing up with the sensors

[@whodoyouknowme258]

the problem i bet comes back every few weeks. there is no fix. you can clear the code with a obd2 scanner, then drive it until you need to clear the code again. rinse and repeat. there is no fix except for a new car.

[@DallasAutoDiag]

I think I did a follow up on this case for like a month and then the lot owner never mention it to me. so I guess the buyer was happy.

[@sterlingwitherspoon5709]

Extra long ass video…what was the FIX..?

[@ALFREDOCHANGOMORENO]

Same thing What was the fix ?