Possible Onboard Diagnostic computer system problem
 

I recently got my brother's 2000 Altima GXE and he never mentioned to me about a problem he had when he went for his emissions test. From the report he got from the mechanic said that we they were attempting to perform an Onboard Diagnostic test, there was No signal coming from the Onboard Diagnostic computer system.

What I would like to know is...will this affect other areas of the car or just the emissions testing? Do I need to have anything replace? Also, how much would this cost at a dealership and is this something I can do myself? Any help or recommendations would be appreciated.

Thanks.