2003 chevy silverado

This truck has been a good running truck until recently… lately you can drive for awhile then the check engine light comes on… readout says reduce engine power… if you stop for like 30 seconds or less and restart all is fine . it doesnt do this all the time or every time has done it once a day or 4 times in a row, never a rhyme or reason to it. I have used my computer reader to see if i can find the problem myself but for some reason the reader cant read ( still trying to trace why… even the free scan from oreillys couldnt link to my onboard computer for some reason) so here i am asking for help, does anyone have any ideas as to the problem or to the onboard computer not linking to any reader?

this is NOT a hybrid… my fault it is a 1500 hd

Wiring or dead computer. Dealer may be able to reflash the programs. Scanners and independent mechanics probably can’t help you.

A basic code reader should be able to retrieve the P0 codes from your year of vehicle. If your code reader doesn’t work, and the code reader at the parts store doesn’t work, then one has to assume there’s a problem with the computer itself.