1991 Nissan 240SX Question on EGR and knock-sensor

Since the Check Engine light comes on I retrieved the code from OBD as 32 and 34.
The Factory Service Manual for the car states:
32 - EGR function - EGR valve does not operate. (EGR valve spring does not lift).
34 - Knock sensor circuit - The knock sensor circuit is open or shorted. (An abnormally high or low voltage is entered).

I need to know if it really could be that both EGR and knock-sensor circuit have problems or fixing one should get rid of the other problem. Also if such is the case then which problem needs to be tackled first !

Thanks