P1491 NISSAN - ultima

Question

How do I check to see if the vacuum cut valve bypass valve is working & if any of the connecting hoses are blocked. If so how do I clear them or replaace them? Is there anything else that I should know about this code and why it occurs? Is this a common error and if so is it a problem with the valve. Can it be repaired or does it have to be replaced?

Answer 1

Hi there,

The most common cause for this code is the VC bypass solenoid It stops working because of it's location and causes the code. As for the lines, check to make sure none of the steel lines have holes rusted into them, this can also cause it. You can test the solenoid by removing it and adding power and ground to make sure it clicks.

The VCV itself rarely fails but I have seen them melt when the exhaust gets broken.