DTC P1441 means a warning about EVAP system flow during non purge condition.
This deals with the purge solenoid, vent solenoid, charcoal canister, all the vacuum lines in this system, as well as the gas cap. Any one of these components may contribute to this code being set. All the wiring should be tested including the connectors for any problems. Vacuum lines should be checked for cracks or loose connections. The canister may be damaged or not working properly.
However, the most common cause of this code on nissans is the evap vent control valve. It is located on the evap canister, under the rear of the car by the gas tank. Its the only electrical device attached to the canister itself.
Previously, there's a few things to check here. If you are sure that you don't have a wiring harness problem (these are notorious for the harness wearing through) then you need to check both the components that the code covers. This code covers both the vacuum cut valve bypass valve (the electronic solenoid) and the vacuum cut valve itself (small round plastic valve.) Here's a picture of both of them attached to each other:
If you are absolutely sure that the electronic solenoid is doing it's job, and that none of the hoses are pinched or blocked, you need to check the vacuum cut valve for functionality. Here's how you do that:
1. Plug port (C) and (D) with fingers.
2. Apply vacuum to port (A) and check that there is no suction from port (B).
3. Apply vacuum to port (B) and check that there is suction from port (A).
4. Blow air in port (B) and check that there is a resistance to flow out of port (A).
5. Open port (C) and (D).
6. Blow air in port (A) check that air flows freely out of port (C).
7. Blow air in port (B) check that air flows freely out of port (D).
Also check to make sure that all hoses are going to the correct places.
Keep in mind that the P1441 is a very hard code to diagnose, as it's very "general". There are a list of things that can cause this code, and there is a TSB (Technical Service Bulletin) issued by Nissan that states it can even be faulty ECM (Engine Control Module or On-board computer) programming.
Here is a list of possilble causes:
Incorrect fuel tank vacuum relief valve
Incorrect fuel filler cap used
Fuel filler cap remains open or fails to close.
Foreign matter caught in fuel filler cap.
Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve.
Foreign matter caught in EVAP canister vent control valve.
EVAP canister or fuel tank leaks
EVAP purge line (pipe and rubber tube) leaks
EVAP purge line rubber tube bent.
Blocked or bent rubber tube to EVAP control system pressure sensor
Loose or disconnected rubber tube
EVAP canister vent control valve and the circuit
EVAP canister purge volume control solenoid valve
Absolute pressure sensor
Fuel tank temperature sensor
O-ring of EVAP canister vent control valve is missing or damaged.
EVAP canister is saturated with water.
Fuel level sensor and the circuit
EVAP control system pressure sensor
Here is the TSB issued by Nissan...
Date: August 30, 2000
2001 PATHFINDER; MIL "ON" DTC P1441 (EVAP VERY SMALL LEAK) STORED IN SELF DIAGNOSIS RESULTS
APPLIED VEHICLE: 2001 Pathfinder(R50)
If an applied vehicle has a MIL "ON" with DTC P1441 (EVAP Very Small Leak) stored in Engine Self Diagnosis results, the cause may be the ECM program.
There is an updated ECM program available to address this incident if it should occur.
Hope this helps; keep us updated about your advance.