# Code P1490



## lee1033 (Nov 12, 2016)

I've had a lot of little things going wrong with my truck as of late. The Code P1490 came up when my truck started running really rough two days ago. Prior to this the Code P0301 came up with a misfire on cylinder 4 but that was about three weeks ago. I couldn't find any issues with the new spark plugs, wires, distributor cap and rotor that I had just installed about two months prior. For some reason the truck code went away and the truck was running normal again. Now, about three weeks later I get a new code for a misfire on cylinder one with the P1490 code which hadn't shown up previously. In between changing the spark plugs and the code that came up two days ago, I had a radiator hose that blew out so I decided to check and change all hoses that needed to be changed due to the age of my truck. I found that somehow the tubes for the Heater Core had been previously broken and glued back together so I ended up having to change the Heater Core also. 

I've been doing research and it appears the misfire codes are related to the P1490 issue but I'm not sure. It looks like I may need to change the EGR valve to solve this problem. Any input would be greatly appreciated.


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## smj999smj (Jan 1, 2006)

Year and engine of Frontier would be very helpful. P1490 has nothing to do with your EGR system, rather, the evaporative emission system, which stores fuel tank vapors in a canister until the vapors can be later routed to the intake manifold and burned during the combustion process. P1490 refers to the vacuum cut valve bypass valve. I doubt that this has anything to do with your rough running condition, but it wouldn't hurt to check the vacuum lines on the valve and make sure one of them is not leaking. Also, P0301 is triggered for a cylinder #1 misfire; a cylinder misfire on cylinder #4 should trigger and P0304 code. If this is, by chance, a VG-series V6, it's not uncommon to have driveability issues to do a faulty distributor or a bad fuel injector. Once we get more info on your vehicle, we may be able to give you more advice.


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## lee1033 (Nov 12, 2016)

Trim

SE
Bed

56.3 in. Styleside
Body Style

Crew Cab 4 Full-Size Doors
Brakes

Power Front Disc and Rear Drum, 4-Wheel ABS
Drive Type

Rear-Wheel Drive
Engine

3.3L V6 Gas
Mfr Body Code

D22U
Spring Types

Front Torsion Bar and Rear Leaf
Steering

Power Gear
Transmission

Jatco 4-Speed Automatic Transmission RE4R01A


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