P0325 code,...is this from recent work?

[moho]

Hi all,

I recently got a 2003 GT,...just had a new rad installed,...now the engine light is on. I get the p0325 code when I checked the dash thru the key turn access (3 turns). What are my choices here,....the fluids are all good,..but this is a knock sensor. the previous owner only ran regular,...I put in some high test., but put in some regular and this light came on. Is this the reason for the fault? I just thru some octane boost in tonight,....will this help?

thanks and a appreciate the replies!