I was in 2003 Cesnna 172SP today. Like most 172SP's i've experienced, it has bandix/king gps/comm/nav system.
I shot an ILS yesterday using NAV 1 and it was fine. However upon trying to be established on a Localizer using Nav 1(vor) at a different airport, it was not able to detect the needle to final course on a localizer. When I tuned up Nav 2, it was able detect the course and I was able to shoot the approach using Nav 2.

Do you guys know if this is a malfuction with the Reciever #1 or is it something else that I missed?

Yes, I know that there is button you can push to make it switch from NAV/GPS. I tried both setting and NAV1 was still unable to detect the Localizer.
HOWEVER, it had no problem detecting ILS back to my airport.
Vor check was done on ground and it turns out fine.

Could it be Auto pilot?

THanks!~