2015 V-6 secondary air pump question

I have a 2015 Tacoma V-6 with 50000 miles. I started my truck this morning and heard a really loud rattle coming from the engine bay for a couple of seconds then it went away. Drove 20 mins to work with no problems and no check engine lights. When I shut the truck down I did not hear the secondary air pump whirring sound I always hear. I have searched for this issue but the only problems involve a check engine light. If the pump is inoperative but the valves and switches are good will there be a check engine light for the secondary pump only? It was around 40 degrees this morning so sometimes the pump will cycle when it is this cold. So I am wondering if the fan impeller went bad during this cycle right after start up.