I purchased OBD2 Reader ...
however it did not or would read the Maxima obd2 port ...
Have since found that is quite common with this model/year maxima lol
however this was not a wasted purchase as it reads my other Vehicals fine ..
So .. Solution was to Disconnect Battery neg Terminal with head lights turned on ... then also Disconnect Postive lead ... connect + and - leads with a jump lead ... i left the circuit connected this over night ... when i re installed battery the error codes had been canceled..
the error had occurred because i had disconnected the Air flow monitor and accidentally not reconnected before restarting motor ... prior to that there was not error code on instrument panel lol
... otherwise the Maxima is a great drive especially when it's run on Either 98eń or 100en giving about 8ltrs100km when using cruise control ...

Especia

 

Yes that's normal, if you unhook the battery it should clear the CEL and unless it trips the fault 3x when you hook the battery back up, it won't come back