Error codes p0120 p1516 p2135.....ugh

[Kingx1]

So I left the barber yesterday and started my truck up. Bells start going off and it says "reduced engine power" and the truck has very low power for sure. I turned the truck off and waitied for a few minute to start it back up. Truck started up and ran normal again but still has the cel on. I scanned it and came up with the codes p0120 p1516 p2135. I really hope thus isn't gonna be something that I have to chase around. I did some research and the fix was like 30 different things! Everyone that fixed it said it was something different that was the cause. All the way to the ridiculous alternator fix!

 

[Jblaze10]

So I left the barber yesterday and started my truck up. Bells start going off and it says "reduced engine power" and the truck has very low power for sure. I turned the truck off and waitied for a few minute to start it back up. Truck started up and ran normal again but still has the cel on. I scanned it and came up with the codes p0120 p1516 p2135. I really hope thus isn't gonna be something that I have to chase around. I did some research and the fix was like 30 different things! Everyone that fixed it said it was something different that was the cause. All the way to the ridiculous alternator fix!

Hey man, I have the same 3 codes except po506 u had po516. What was the problem if you mind sharing? Thx.

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[6speedblazer]

sounds like a bad throttle body.

first thing is to do is remove it and clean any and all carbon off the backside.

 

[Maximus1]

Well I can tell you that I had the exact (pardon my frenchy) limp d.ck reduced power problem that really pissed me off. I’m a problem solver it’s what I do but this thing threw me for a loop and then some. I’m an ASE mechanic with 25 years. I tried everything replacing the drive by wire sensor 4 times and every time I did it worked for a little while but the dreaded REP would reappear. Cleaning the throttle body and even removing the motor inside the throttle body and replacing it with one that I know was good and still the REP code would come across the display screen. I got so frustrated that I was really considering a match and a five gallon can of e85. In the end it ended up being the voltage regulator built into the alternator. As soon as I had the regulator tested and it showed bad I replaced it and that lady’s and gentleman fixed my problem. My recommendation is to take it to Autozone and get a MANAGER who can test the voltage regulator ACCURATELY and have them test it on your truck in the parking lot and save you a lot of time and headache. or you can do what I did and chase it for three months and buy a bunch of parts that you don’t need.

Make sure that you tell them that you want the regulator tested not the alternator because the alternator can still pass even with a bad regulator.

 

[Maximus1]

What really sucked it when it would go into reduce power mode on the highway. Kingx1 keep me posted on what you find.