hello everybody, I recently just scanned my friends 98 altima gxe for any codes since his check engine light was on and found 3 of them, 2 of which have something to do with the evap control system specifically the canister. the codes are P0325, P0440 and P1448 (which is in a "pending" state). P0325 says its a "knock sensor 1 circuit malfunction". I'm assuming the knock sensor 1 is gone, has anyone replaced it? I just need to know where it is on the car.

P0440 apparently means the canister purge solenoid has failed or the canister is plugged or not working as it should. and the one thats pending P1448 has something to do with the canister purge valve. Has anyone tested this system? I don't really know how to test or pinpoint the problems in the evap canister system, I can replace everything but that seems to be a waste of money and time.

Any help anyone can lend me or just a point in the right direction is very much appreciated!! thank you in advance.

hello again everyone, alright so I just replaced the sway bar end links on said altima yesterday, and decided to scan the computer again with the obd2 scanner. the engine light was still on but this time it found no codes. I waited 10 mins tried it again, still no codes, drove it around for a bit did it again and no codes. so i ended up just turning the light off for him. Does anyone know whats going on here? Is this a normal thing or is there a fault in the system somewhere? I'm a beginner at computer codes and don't know why the codes seemed to have disappeared. thank you.

worked on a car with a p0440(i think thats a small evap leak), turns out she didn't have the gas cap fully sealed one time. cleared it and it never came back. you can test the evap on cars sometimes with the scan tool depending if it's factory or generic, some generics can do it though. go to special functions and you should find a purge seloniod on/off control. other cars you have to crimp the hose to the vent seloniod. close it and use a smoke machine to find the leak.

I have a 2002 altima code P0442. I think I will replace the purge valve solenoid and it will be easier if I move the sway bar. Hope its not hard to do. Has anyone ever done this repair before?