A 2001 Frontier (D22) or Xterra (WD22) may exhibit one or both that the adhering to symptoms: MIL "on" v DTC P1491 (Vacuum reduced Valve Bypass Valve – VC CUT/V BYPASS/V) stored in the ECM; and/or challenge refueling the vehicle. The vehicle’s fuel tank might need to it is in replaced. Usage the suitable Service Procedure listed in this bulletin come diagnose and also ….

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MIL “on” through DTC P1491 (Vacuum cut Valve Bypass Valve – VC CUT/V BYPASS/V) save on computer in the ECM; and/or difficulty refueling the vehicle. The vehicle’s fuel tank may need to it is in replaced. Usage the ideal Service Procedure noted in this bulletin come diagnose and also repair these incidents, if they have to occur.

Service Procedure:

Warning: prior to performing any kind of of the service Procedures below, be certain there space no ignition sources (i.e., open flames, sparks, etc.) in or roughly the vehicle/work area. Make sure the ideal rated fire extinguisher is accessible for instant use.
MIL “On” with DTC P1491 Stored:1. Connect CONSULT-II.

2. Rotate the ignition vital to “on” yet do not start the engine.


4. The press sensor value should read between 3.32 and 3.40 volts (3.36 volts is the nominal value):

If the value is between 3.32 and also 3.40 volts, continue to action 5 below. If the worth is not between 3.32 and also 3.40 volts, refer to the EC section of the vehicle-specific company manual for diagnosis that DTC P0450 (EVAP device Pressure Sensor) to repair the vehicle.

5. Start the engine and enable it to idle.
6. Monitor the EVAP push Sensor value with the engine idling:

If the EVAP device Pressure Sensor worth decreases an ext than 0.02 volts from the reading displayed in step 4, the EVAP Purge Volume regulate Solenoid Valve (in the engine room) is leaking engine vacuum (not sealing). Change the EVAP Purge Volume regulate Solenoid Valve. If the EVAP mechanism Pressure Sensor value decreases much less than 0.02 volts native the reading shown in step 4, or go not change at all, change the fuel tank and O-ring.

Note: refer to the vehicle-specific business manual, ar FE (Fuel and also Exhaust)/Fuel System/Removal and also Installation/Fuel Tank for detailed instructions on fuel tank removal and installation. Follow all warnings and also cautions provided in the company manual.
Difficulty Refueling the Vehicle:1. Usage a suitable an equipment to eliminate the fuel native the fuel tank.

2. Examine that the two steel pipes attached come the Fuel Filler Neck room clear (See Fig. 1).


note the pipes and also hoses prior to disassembly. Usage duct tape and an indelible mite (See Fig. 1). This is therefore they have the right to be correctly established for reassembly. If the hoses are later on reconnected incorrectly, refueling challenges may occur. one of the pipes has actually a restrictor within of it and also will circulation slightly much less than the other, however, they need to both be clear (not blocked). The pipe v the restrictor is linked to the reduced of the two nipples ~ above the fuel tank. This is the signal line. The upper nipple is linked to the filler neck pipe there is no a restrictor in it. This is the recirculation line.

3. Remove the huge diameter refueling hose that attaches onto the charge port the the EVAP canister (see Fig. 2).

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4. Shot to refuel the vehicle:

If the automobile is no longer an overwhelming to refuel, check the EVAP canister and water separator and also hoses because that restrictions/debris and also repair/replace together needed. If the automobile is still an overwhelming to refuel, change the fuel tank and also O-ring.

Caution: Remember come reattach the hose disconnected in step 3.