p0509 code on Monte Carlo

Hello,
Not a lot of facts on this yet. My father has a Monte Carlo that based on images I have seen on the net looks like around a 1999 model. V6.

It is not running right, getting code P0509 on his computer readout. Manual says ""idle control system circuit high"... Now what does that mean?

Any ideas based on the small amount of facts?

Regards,

Redbug2

I do not see p0509 in the obd11 list, recheck that.