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Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 18548
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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2003 Nissan Xterra SE: the vacuum cut valve bypass valve

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p1491 code coming up on a 2003 Nissan Xterra SE/SC. It is stated as the "vacuum cut valve bypass valve". What are the steps to verify exactly what is the problem and what needs to be replaced?
Hello and thank you for using

HERE is all the disgnostic steps from the Nissan Service Manual on how to diagnose that code with the wire diagram.

If you have any more questions on this, please feel free to ask. Thanks Jay!
Customer: replied 6 years ago.
I have two more questions. How would I counduct this test without the consult-ll? I have just a code reader. It also states that if a "NG" is displayed, refer to EC-1681 "Diagnostic Procedure" and there is no EC-1681"Diagnostic Procedure". What is the EC-1681 "Diagnostic Procedure"? Also does "NG" stand for no good and continue troubleshooting?
If test are NG No good, they want you to check the vacuum cut by pass valve. That is the plastic valve in the back with the 4 hoses going to it. The way you will have to diagnose it is to check the vacuum cut solenoid and check all hoses. You may need to pressure check the Evap system and see if it holds pressure. graphic

Thanks Jay!

Edited by Jay on 5/16/2010 at 1:30 PM EST
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