Reduced engine power code

[noco-k5]

My 2004 Suburban 2500 just threw a code and displayed reduced engine power as it entered limp mode. I pulled over and it ran fine again. Any ideas what the cause might be? It has a 6.0 with 133k miles. I love the Suburban since getting it earlier this year but I've already had a couple of problems with it. Bought it based on reading these trucks were reliable well past 200k. Hasn't been the case so far not feeling real confident about taking it on a long trip unfortunately.