Engine will not stay running and codes p1516 and p1518

2003 CHEVROLET SILVERADO
380,000 MILES • 5.3L • V8 • 2WD • AUTOMATIC
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STEPHO63
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Changed 02 sensor, truck wouldn't start. Tried resetting ECU by pulling fuse and disconnecting battery. Truck starts but shuts off immediately. Showing codes p1516 and p1518.
Nov 22, 2021 at 9:31 AM
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SQM
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Hello,

Those two codes are for the throttle actuator and the throttle position sensor.
Fault within either of those can prevent the engine from running.

Best course of action would be to trouble shoot those code. It could be due to a bad sensor or wiring.

I have attached the troubleshooting guide for both P1516 and P1518 below.
Going through those steps can help you determine the issue.

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.
Nov 22, 2021 at 2:13 PM
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SQM
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Another point, this issue can also happen due to a dirty throttle bore. Cleaning out the throttle bore could be a good place to start.

Here is a helpful guide:

https://www.2carpros.com/articles/throttle-actuator-service

I have also attached the throttle bore removal and cleaning procedure below for your reference.
Nov 22, 2021 at 6:16 PM
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STEPHO63
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Thanks. I will try all of that and hopefully find the problem. I will let you know how it goes.
Nov 22, 2021 at 7:37 PM
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JIS001
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I would agree SQM with the throttle body bore service. When it comes to correlation codes between the pedal and throttle, if the throttle had too much carbon it will not respond to the pedal command as fast as it should.

The throttle clean will be the cheapest fix to start with. One thing to point out is to never disconnect the throttle connector or things will get worse. Remove the throttle (pull out) with the connector plugged in still. This should give you space to clean the front and rear of the throttle bore and plate. Once clean, install throttle back and check idle.

Let us know how that works out. If you have some idle issues after disconnecting both battery cables and touch the leads together for 15 minutes to erase the old learned values. Keep us posted if this procedure works with cleaning the throttle.
Nov 22, 2021 at 9:39 PM
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STEPHO63
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Well, I cleaned the throttle body, checked all the grounds I could find and same issue. Starts but immediately shuts off. Is there a fuel shut off somewhere because it acts like it's out of gas? I rescinded it and it's now not showing any codes. I'm confused!
Nov 23, 2021 at 1:45 PM
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SQM
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See if you can go through that trouble shooting guide. As the issue exists the code should come back on again.
Nov 23, 2021 at 9:33 PM