My 2001 Nissan Altima's OBD codes are P0325 and P1126. Could be the possible resolutions for these codes?

P0325 is for the Knock Sensor (KS) circuit. The diag for that is extensive and usually lead to the knock sensor needing replaced.

P1126 addresses the coolant taking too long to reach operating temperature, thus the Engine Control Module (ECM) not being able to go to closed loop (ask me what that means in another post). Replace the thermostat and refill the system with fresh 50/50 mix of coolant. Purge the air and the code should not reappear.