Nissan Code P0446 & P0440

I have a 1997 Nissan Sentra. Service Engine Soon light came on the other day. Auto Zone retrieved the Codes P0446 & P0440 which points to the area of the EVAP purge/vent solenoid. Three days before the light came on I changed the oil MYSELF for the first time (girl friend's car). The oil filter is located in a bad place and I had a heck of a time getting at it. I noticed in the service manual that the EVAP Purge Control Solenoid Valve may be located near the oil filter (haven't crawled under there yet to look). I am wondering if I inadvertently pulled a vacuum hose off or damaged something. It is hard to tell in the service manual picture if the Purge Valve is indeed located near the oil filter. Any thoughts on this or the codes? Thanks.

it's a likely scenario

I think is not located near the OIL filter.
I think it located near the fuel tank.
Are you sure these codes weren´t before ?

P0446 is referring to ONLY the VENT control solenoid. The PCM detected a Voltage short or open onthat circuit and set the code. P0440 could be as simple as your oil change, but I can't see any way that changing the oil can cause an unexpected voltage anomaly in the vent control circuit. Id find out if the light's been coming on and off in the recent past.

OK boys I found the problem. At a small bend in the intake manifold I found a very small crack/hole about the size of two pin heads producing a small vacuum leak. Looks like very thin metal in that area and probably was that way in the manufacturing process of the manifold. I believe Nissans are noted for thin metal areas. Anyway...I patched the crack/hole with some JB Weld, reset the ECU and haven't had a problem since.

hm, sounds a little suspect to me. 0446 is a circuit code, which means it can't be set by a vacuum leak. Anyway, hope it's fixed, but if it aint, make sure you let us know.

I agree with darkrooms.

the problem should be in the vent valve.

Keep posted.

What about the other code that I received...the "P0440" along with the P0446? when we looked both codes up in the Auto Zone's computer inside the store, one of the symptoms that was indicated was "Check for vacuum leak." Thanks.

Yes, for 440, but not for 446.

Actually, the problem is in the Vent Valve, probably a faulty vent valve that should be changed (first inspect it and be sure ).

Well....It's been 300 miles since I fixed the vacuum leak. I put my scanner on the car yesterday and it returned no codes. The vent valve in this car operates on vacuum. My thoughts are concerning any codes...they do not 100% pinpoint the exact problem. They are merely a "tool" to get you pointed in the right area. I have found that if you are not open-minded you may end up spending a lot of time and $$$ for nothing.

Well, in my experience overthe last 11 years diagnosing these "shadowy, tenuous codes" they have specific setting parameters. They only set for extremely specific reasons. Now, no one was saying to not fix the obvious problem that you had, we only encouraged a little more electrical diagnosis in case the light came back on. We're well aware of the difficulty in diagnosing drivability codes.

I have a 1997 nissan sentra gxe. I also have the the same code problem for the evap system after the light had came on and had it checked out. however, i replaced evap solenoid valve, air filter, spark plugs, distibuter cap, gas cap looked for any loose hoses. I noticed that the hose that looks like it may have been hooked into the maf sensor right next to the wire connector doesnt even look like air is going to flow in or out of it if it was plugged into the sensor it is sealed closed does this hose just need to be closed off? does it have to go into the sensor if the hole it looks like it went into is just sealed off? I can not see anyother place where it would go. there is a clamp on the hose that keeps it in the area that it leads to... so that is the only spot i see where it could go. I have had this problem for some time. i really would like to find out why I have the check engine light still on. I tried replacing the cheaper things 1st. i am hoping it doesnt come to having to replace the evap canister because it looks like that is something that i have to get from nissan. i know since i have had this problem i am having terrible gas milage and my car doesnt really start up off the bat like it once did. can having a maf sensor that is bad also give these codes as well. I know it will make for bad gas milage and bad starts from what i am reading. im hoping that someone will have some info that may help me see what measure i may have to take to fix this. and if this hose does indeed go pluged into the maf sensor right next the wire connector that plugs into it.

I would seriously recommend being a little "open-minded" and checking your intake manifold for slight vacuum leakes. Check for any small pin holes especially, as I stated in my case, near any metal where a slight bend, curve, or any shallow hollows. I just had mine state inspected and it passed with no codes. Remember...don't get off on some tangent spending $$$. Check for the obvoius first that costs nothing. Let us know what you find. Thanks.

Where is the Vent Valve located? Thanks.