# Code P1490



## twgables (Feb 8, 2007)

My 2001 Pathfinder 220,000 Kilometers has had the engine light on since I bought it with 40,000 k's on it. Took it to the dealer and had then service and replace a gas sensor but the light came back on. The latest code is P1490....they seem to think there may be a short in the wiring! Can anyone help me as I am not very mechanically inclined and by the way a woman...thanks


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## smj999smj (Jan 1, 2006)

Well, first of all, if the check engine light illuminates, i would recommend you have the problem diagnosed before you rack up another 180,000 kilometers!

P1490 indicates the ECM received an improper voltage signal from the vacuum cut valve bypass valve, which is located under and to the rear of the vehicle, not far from the coil spring. It's an electric solenoid valve that controls the flow of vacuum as part of the evaporative emissions system self-test. The usual cause is the solenoid sticks, meaning that the vacuum cut valve bypass valve should be replaced, but a short or open in the harness to it, or a poor connection in the harness connector, could set the code, as well. 

The P1490 code has nothing to do with the gas sensor (I'm assuming you are referring to the exhaust gas sensor, AKA "O2 sensor?".....If so, did the update the ECM in the process as per the TSB regarding O2 sensor incidents?).


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## twgables (Feb 8, 2007)

So what would be the effect of this problem? Would it cause a loss of power and what would be the approx. cost to rectify it? Thank you so much for your help!


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## smj999smj (Jan 1, 2006)

The effect would be that the ECM would not be able to self test the evaporative emissions system. It wouldn't have any effect on drivability, only the ability to get the vehicle through an emissions inspection and the effect on the environment, if the evaporative emissions system is not working properly.

If it is the valve and assuming there is no harness problem, I would ballpark the valve somewhere between $35-$55 +/-. It takes less than an hour to replace.


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## twgables (Feb 8, 2007)

Thanks again for your valuable assistance.Regards, M


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## cupton (Oct 29, 2007)

smj999smj, I am having the same issue. Can you tell me if this valve is a 12 volt valve? Can I test it w/ battery voltage? Thanks for any help..


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## drcarfix (Aug 1, 2013)

*Power/Ground*

TO: smj999smj

The computer is not sending the signal into ground. I got 13 volts at the computer. Does this mean I need to replace the computer? Alldata does not provide me with any further details. I traced the wires and have good continuity through out. I am able to here the solenoid click with my scan tools. However, I am stuck at this moment. Please advise. 

P1490 indicates the ECM received an improper voltage signal from the vacuum cut valve bypass valve, which is located under and to the rear of the vehicle, not far from the coil spring. It's an electric solenoid valve that controls the flow of vacuum as part of the evaporative emissions system self-test. The usual cause is the solenoid sticks, meaning that the vacuum cut valve bypass valve should be replaced, but a short or open in the harness to it, or a poor connection in the harness connector, could set the code, as well.


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