Reduced engine power

Question edited for clarity.
Question moved to model category.

Yes, aftermarket alarms can cause problems like that, and remote starters are even worse. Better to stick with what the factory designed and put in.

The check engine light has a code and that will tell you what the issue is. You need someone with a scan tool.

2003 Silverado 2500HD REDUCED ENGINE POWER - Discussion on Topix

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Dec 28, 2009 - 20 posts - ‎12 authors I have replaced the throttle body, had the wires re-connected and .... The gauges all went wild and reduced engine power displayed on the dash. I looked it .... The truck just went to idle for no reason and it keeps happening. 2003 Chevy Trailblazer-CHECK ENGINE LIGHT AND ...
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Reduced Engine Power Message Displayed on GM Vehicles

www.underhoodservice.com/tech-tip-reduced-engine-power-message-dis...
Dec 10, 2012 - Tech Tip: Reduced Engine Power Message Displayed on GM Vehicles ... Model year 2008-'10 vehicles must have the engine control module (ECM) reprogrammed ... Do not drop the electronic throttle control components.

tech 2 require to reset radio. take to dealer

REDUCED ENGINE POWER.HAVE VECHICLE SCANNED AT DEALERSHIP BECAUSE YOUR ENGINE HAS A MECHANICAL FAILURE.LIKE POWER STEERING PUMP OR APP SENSOR FAULT.I

The radio is flashed with the serial number of your truck to operate. If change the replacement radio will have to be flashed as well. Chevy dealers do just that

How to Reset GM Theft lock Radio's
Article Disclaimer: This article is meant to be used by Delco Radio owners to reset there radios. In no way is it meant to be used for any unethical or unlawful ways.

Purpose
The following instructions will allow you to reset any GM (General Motors), Cadillac, Oldsmobile, Buick, Pontiac theft lock radio.

Requirements
The theft lock radio must be in "LOC" mode.

Procedure:
1. Turn the ignition ON (The radio should display "LOC")
2. Hold down the Radio Presets 2 and 3 buttons for six seconds
3. The radio display changes from LOC to a three-digit number. Write this number down. You now have fifteen seconds to complete the next step.
4. Press the AM/FM button
5. The radio display changes to another three-digit number. Write this number to the right of the first one
6. You now have a six-digit number, the first three digits are from STEP 03 and the last three digits are form STEP 05
7. Call 1-800-537-5140
8. Press 1 then # (pound). You'll hear "Invalid Code, try again"
9. Press 139010 or 106010 or 206010 or 202107 then # (pound). You will be asked to enter your four or six digit code followed by *
10. Enter the number from STEP 6 then *
11. Listen to the four-digit number and write it down. It will be repeated twice
12. Turn the ignition ON (The radio displays LOC)
13. Use the MN and HR buttons to enter the code from STEP 11
14. Press the AM/FM button. The radio display changes to "SEC". Your radio is now "un-locked" and usable.

Dealership Codes
139010
106010
206010
202107

Troubleshooting
If you fail to enter the correct code eight times, the radio goes into INOP mode. You have to wait an hour with the ignition on before the radio returns to LOC mode.

To Read the original article or read similar articles please visit kingbain.com/how-to/unlock-gm-theftlock-radio-s

Good luck (remmeber comment and rated this).

the only way to get the right code is to contact your local dealership and get it from them

The dealership is the only place that I know of that can unlock the radio. Unless you find a "use to be" mechanic with the procedure to unlock it. Installing the radio, research goolge, i have seen a website with info for doing that. I dont remember what the site name is, sorry.

i had a problem similar to this. what i did was i took it to the dealership where i bought it at and it was the EGR valuve that needed to be replaced. i ended up paying about $500 for the whole thing because i had it installed at the dealership. you can order the EGR valuve and install it on your own. it takes about ten minutes to install it.