Another reduced power thread 03 denali

well as the title indicates, having issues with reduced power on or 03 denali. I haven't done too much with it yet, but pulled some codes. a couple that I knew where there, and a couple that surprised me a little, but not too much if there is other electrical issues. guess it is time to get after them.

it started not long ago and did it twice the day it started doing it. this seemed to stay pretty consistent for the next week or so, so till she took it one night and on her round trip of about 60 ish miles it did it 9 times total during basically a blizzard ( and the truck it white, so a white truck along side the road in a blizzard is less than ideal) so she is driving the Tahoe and I am running the 2500 burb daily for couple weeks.

codes as follows.

p0134 - O2 circuit insufficient activity bank 1 sensor 1

p0135 - O2 heater bank 1 sensor 1.

figuring the heater code popped up first, just haven't changed the sensor yet. will change that and go from there

p0452 - fuel tank pressure sensor circuit low voltage

p0463 - fuel tank level sensor circuit high input

p0522 - engine oil pressure sensor circuit low voltage

p1516 - throttle actuator control module actuator position performance

hoping the ground wire fixes will take care of most of this.


will be doing some ground wire upgrades, planning on doing pcm, body, engine and probably an upgraded wire for the power from the alt to the battery. as well as check the wires at the tb and go from there.

will do updates as I have time and weather to get things done.



edit to add that I have been using an aeroforce scan gauge to read and clear codes, as my dongle for torque wont work on this truck for some reason. but when/if I need more I do have hptuners also.

id clean all your grounds first for sure. thats to many codes for every one of them things to be bad.

o2 could be bad that but wont keep ya from running. id change em both if you got higher miles.

well I added a few grounds so far and took a look at the plug for the tb, and no luck so far. gonna have to read the new codes and see what it says. I am feeling a tb in my future.

well with working 12 1/2 hour work days and plenty of overtime and having 3 trucks I have kinda set the denali on the back burner for a min, but yesterday I grabbed my hptuners and had a look a the truck and didn't find anything more than the 1516 code, so I think I am gonna just jump to the next step and try a throttle body as it keeps tossing the tps code.

later I will have to address some O2 sensor, and see what is up with some other things, but need to get it reliable again first.

bigdog9191999 said:

well with working 12 1/2 hour work days and plenty of overtime and having 3 trucks I have kinda set the denali on the back burner for a min, but yesterday I grabbed my hptuners and had a look a the truck and didn't find anything more than the 1516 code, so I think I am gonna just jump to the next step and try a throttle body as it keeps tossing the tps code.

later I will have to address some O2 sensor, and see what is up with some other things, but need to get it reliable again first.

Click to expand...

Tb could be fine. Could be the plug going to the tb. Over the years from all the vibrations of the motor the tb plug can develop breakages in the copper wire strands causing a reduced engine power condition. They sell replacement plugs for this.

Thought I updated this one. I tossed on a TB after looking the wires over as they looked ok,. It was basically normal after the tb, the idle was high for a little bit but it learned after about a week and is all good now. Maybe a little touchier on initial throttle. But am down to just the O2 codes.

Tonyrodz said:

Tb could be fine. Could be the plug going to the tb. Over the years from all the vibrations of the motor the tb plug can develop breakages in the copper wire strands causing a reduced engine power condition. They sell replacement plugs for this.

Click to expand...

The plug or the TPS (Throttle Position Sensor) which gives feedback to the TAC Module of the throttle postion. (I know you know this Tony). Dead spots on the wiper traces caused by normal wear and tear over the years will cause temporary or even immediate loss of feedback voltage to TAC Module which will trigger a "Reduced Engine Power" limp mode. This failsafe is to prevent throttle runaway in DBW C and K chassis vehicles. Easily replaced and can be bought with or without a replacement plug and pigtail which will need to be spliced into factory wiring going to the TPS at the Throttle Body. Factory rivets hold TPS in position and are replaced with screws that come with replacement TPS. It is indeed not uncommon at all for the factory wiring harness to get a broken wire (stranded wires) about 2" from the TPS or so. You wont physically see the break because the insulation is not broken.

That was gonna be my next step, but thankfully so far the tb has done it ( guessing just the tps).

rockola1971 said:

The plug or the TPS (Throttle Position Sensor) which gives feedback to the TAC Module of the throttle postion. (I know you know this Tony). Dead spots on the wiper traces caused by normal wear and tear over the years will cause temporary or even immediate loss of feedback voltage to TAC Module which will trigger a "Reduced Engine Power" limp mode. This failsafe is to prevent throttle runaway in DBW C and K chassis vehicles. Easily replaced and can be bought with or without a replacement plug and pigtail which will need to be spliced into factory wiring going to the TPS at the Throttle Body. Factory rivets hold TPS in position and are replaced with screws that come with replacement TPS. It is indeed not uncommon at all for the factory wiring harness to get a broken wire (stranded wires) about 2" from the TPS or so. You wont physically see the break because the insulation is not broken.

Click to expand...

You explained it way better then I ever could! You the man @rockola1971! Good to see you back.

bigdog9191999 said:

That was gonna be my next step, but thankfully so far the tb has done it ( guessing just the tps).

Click to expand...

Yes, it was the TPS. Worn beyond its service limits. I bought my 05 Yukon Denali on the cheap because it had the same problem which is why I already know about this circus. Your throttle body was fine and just couldve used a good cleaning and a replacement TPS installed. Mine was around $100 for the TPS.