Q: Horn on 2003 Kia Sorrento ex will only blow sometimes & dash light will only work sometimes.

I just recently bought this 2003 kia sorento ex from a dealer with 200,000 miles on it. Seems to be in great shape but the day after i bought it home i noticed the horn wouldnt blow & then several attempts later it worked but its still not working properly sometimes its blows sometimes it wont. I hadnt driven it any at night but was goin to & noticed the high beam indicator (blue light in dash) did not illuminate so after switching back & forth it did then illuminate but still same problems sometimes it works & sometimes it dont . Also all of dash lights such as warning lights upon cranking the vehicle sometimes do not illuminate either. Do u think this is a combined related problem or several differnt parts issues? What do u think may be going on as i purchased this as is no warranty but seems to run great..check engine light did come on & i had advance auto check it & got code po174 which was told it may be 02 sensor

My car has 203000 miles.
My car has an automatic transmission.