help code P1605 & P0600

[ham6817]

I purchased a used 98 maxima from a police live stop auction($400). I do not know the history of the car. Most of there cars don't come with keys. I got the started with in the first hour of receiving the car saturday but was able to get a key made on Monday. I noticed the check engine light on so i hope it was nothing major. I scanned the codes and got 2 (P0600 & P1605)

I have read a few things about the P1605 code but really don't know where to start The battery was dead and sits at only 12.3 volts overnight.
(Battery is on my todo list)

Whats the first and cheapest thing to check and rule out first.
I do have an extensive collection of tools.

My plan is to fix the problem and sell it for a profit.
I just hope i don't have to put a lot of money in to. If i do that i'll just keep the car or maybe break even.

So far i'm $80 into it.

[maxhopper]

See page EC-314 for P0600 and page EC-422 for P1605 components and diagnostic information. http://www.nicoclub.com/FSM/Maxima/1998/EC.pdf

[ham6817]

for some reason the link is not showing up.

[ham6817]

ok i was able to read it.Looks like i have my work cut out for me.