P1516 Code - Reduced engine power mode
 

I am in desperate need of help, and hoping someone here has a new idea we haven't tried! Quick backstory here. I am not a certified mechanic, but I have been working on cars for many years. My 2 friends helping me on this are both ASE certified and one actually owns a big shop in my hometown. We have been fighting this issue for 5 weeks now and running out of options to try. I will list below everything we have tried below, and maybe one of you will have a new tip for us to try!

2005 Silverado K1500 with 5.3L motor
We continue to get the reduced engine power mode. The scanner gives code P1516 within seconds every time we clear it out and start another test drive and usually happens just while idling.

LIST OF WHAT WE HAVE TRIED ALREADY:
New throttle body
New throttle position sensor
New throttle body harness plug
New throttle actuator control (TAC)
New gas pedal with sensor
Every ground wire on the truck replaced, while sanding down connections for good ground
Cleaned ECU connector in case of corrosion

And nothing has worked. Can any of you lead me to something else to try please? Thank you!

I seem to recall the "Reduced Engine Power Mode" results from the on board computer sensing a problem and commanding the system to "Reduced Engine Power Mode" . I would research operating parameters that will make the computer set the system at Reduced Power. It could be a TAC error or a pedal position error among several things that will cause the shift to "Reduced Engine Power Mode". Here's a couple of good troubleshooting links. Remember, A "Reduced Engine Power Mode" indication in the dash display does not mean the engine cannot produce power, it means the computer has directed the engine to reduce power output because an unrelated problem has raised an issue that may be aggravated by too much power.

https://www.carparts.com/blog/what-t...he%20%E2%80%9C

https://www.carparts.com/blog/what-t...-engine-power/

P1516
 

I too have ran into this issue. I've done all of the above including the APP sensor with relearn procedure, which is far more complicated than it should be, when I clear and reset the ecm the truck sounds too good to be down and I've replaced every single sensor in the circuit, tested all pig tails in the circuit except 1 which is the app but the pedal works great irl and during live Data test. 1 mistake I did make was replacing throttle body with tps with an aftermarket model. I've read that the cat eyes don't like aftermarket sensors so not sure if it is my issue due to the fact that if it has more than a 0.5 sec response the p1516 will appear. At my wits end and would appreciate any new ideas beyond setting the truck on fire... I love the cat eyes and will not stop until issue is fixed.
Thanks.

@KrudeService
no vehicles like aftermarket sensors. Please post your vehicle info.

There are a few pre checks the vehicle computer does to verify the integrity of certain circuits. If the pre-check does not pass, it will notify the operator either with a code or reduced power condition to insure the condition is corrected before any damage takes place.. Sometimes it can be something like a sensor or a poor or non existent connection.. That is where someone that has the experience AND access to the info is required.
An example is a faulty wheel speed sensor code does not always mean the sensor is malfunctioning, a good part of the time it is just a poor electrical connection. The challenging part is to find it .

Have you inspected the wires in the appropriate wiring harnesses to make sure none are shorting out to another wire or to ground due to worn/broken insulation? I am not talking about the ground wires, but the wires that carry sensor data and Vref?

Good Luck!

In the same boat
 

Ever get it figured out my friend? I've did all of the above myself and still no luck

ABS and/or TPMS can cause
 

If the system finds a problem with ABS or TPMS when running self check, it limits the engine which sets the P1516 but nothing else.