How to clear obd code 325 on nissan quest 00

SOURCE: overheating engin when at idel, fan not working

does both the hoses get hot bottom and top? this will tell you if theres flow through the radiator. If you have a voltage tester test the wires on the fan connecter check there is current going to the fan if so replace the fan its a common problem as previously stated. 
if there is no power to the fan when the vehicle should be turning it on i.e. its hot enough check the fan relay under the hood.

SOURCE: Changed the plugs...

Yes, the code will need to be cleared by the technician.

Usually the check engine light doesn't come back on immediately. However it will store the code until it is cleared by the tech.

If it comes back on immediately, then you have an immediate problem b/c it take a certain number of misfires over a certain number of miles before it trips the code again.

SOURCE: P0155 & P0135

O2 sensors are tricky. sometimes like anything else they fail. many times though the exhaust mixture they encounter is out of their range and that shows up as a failure.since you seem to have no other problems , I would go ahead and change them, but don't be disappointed if the code shows up again (at least you know it's not the sensors.) I don't like using the process of elimination when doing repairs but sometimes you must.

SOURCE: 2001 Jeep Grand Cherokee code P1391

I would check to be sure that the timing chain hasn't jumped at all ..

SOURCE: check engine light codes and troubleshooting

Sounds like you have a vacuum leak for the lean code and the misfires. I don't see a 473 code in my manual, but have a 463. The 463 is for the fuel level sensor open or voltage high.