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04 Nissan Quest P0447

My Quest has a P0447 Code and P0447 pending. Based on what I read the error indicates Evaporative Emission Control System Vent Control Circuit Open. I have replaced the Vapor Canister Purge Valve (Located on the Canister under the rear of the vehicle), but problem still exists. I have read different things online about wiring harness or replacement ECM. Any help would be appreciated to get this figured out.

One of the biggest causes for this in Nissans is chronic overfilling the gas tank. An occasional overfilling usually is not harmful but a steady habit of doing this eventually leads to this failure. You have to stop at the first click. If you are in the habit of overfilling, just stop overfilling and see if the code goes away.

Check your fuses.

Thanks for the info, I appreciate it. I usually do not top off the tank, so overfilling is not the problem. I also checked the fuses and nothing seems blown. Any other possibilities.

The code is for the vent valve circuit. The valve itself is only one part of the circuit. So with any of these the first thing to check is the wiring. This code indicates that the circuit is open. So you probably have a broken/damaged wire or maybe even a problem in the plug. Some problem is not allowing the juice to flow.

I was unable to find a vapor recovery system diagram for this vehicle, however normally there’d be a diaphragmatic valve that opens when the gas is being pumped in that allows flow of the vapors to the charcoal canister. When the pump stops, the valve should close. This is not to be confused with the purge valve, which purges the charcoal canister when the engine is started.

I suspect the term “circuit” is being used by this code to describe the physical “circuit” through which the vapors are allowed to pass rather than an electrical circuit. In short, that diaphragmatic valve may be stuck open. The valve itself is probably located at the top of the fuel pump assembly, but it might be separate, located by the top of the fuel pump assembly.

If someone here can access the vapor recovery system diagram, that would be a big help. Even if it proves me crazy.

I didn’t go look for an evap map. But I did miss the “finer” point of vent vs. purge valve in the original post.

Here is a shot of the vent valve

And here is one of the purge valve

The description indicates that the vent valve is on the canister and purge valve on the engine. Both are electrically actuated. I’m guessing that even though the OP said the purge valve was replaced, I suspect it was the vent valve.

Based on the links you supplied, the part I replaced was the vent valve attached to the canister. It a little confusing with those 2 parts and they are on compete opposite ends of the vehicle. I guess my next part would be the purge valve in the engine compartment. Are there any wiring checks that can be done with a volt meter?

No. There are separate codes for the purge valve circuit. (The equivalent “open circuit” code for the purge valve is P0444). So I would stick with the vent valve circuit. Start with a careful visual inspection of the plug back there at the valve itself. Follow the wires as far as you can, though they often disappear into the looms in short order. You’ll probably want a wiring diagram as you may need to find the other end of those wires after they disappear into the loom. At some point they end up at the PCM. This gets to be a complete pain, but if you get that deep you can start with basic continuity checks. But the thing is that the most exposed and vulnerable area of the wiring is probably going to be back there at/near the valve. Careful visual inspection is the place to start before you even worry too much about where the wires end up.

A factory service manual would tell you how to check for voltage at the vent valve. Someone here might know the “typical” way to do it or even how to do it on this vehicle. I don’t. It will only get powered up under certain conditions, and I don’t know what those are. It’s probably supposed to get juiced with 12V, though it might also be a different voltage. But all of that can be checked with a voltmeter if you know the specs.

From what I can tell, there should be a red wire from the power distribution module going to the vent control solenoid, then from the other side of the solenoid there’s a light green/black wire to the ECM. As part of this circuit there’s also a red/green wire directly from the PDM to the ECM, likewise a white/black wire between the two. I expect if there’s an open in any of those three paths it would throw a code. It looks like when the vent solenoid is active, all three paths (excepting the light green/black wire) should measure at battery voltage or close to it.

The function of this valve is to temporarily seal the canister vent. In normal operation it remains unsealed, and only is activated so the ECM can test if the evap system is working properly.

Edit: There’s a 15 amp fuse in this circuit, number 35 maybe? … Anyway, good idea to check that too.

Where is the ecm located?

Don’t you have access to a service manual of some kind or another for this vehicle? If not – since you’ve already replaced the vent valve – you’ll probably be better off asking your inde shop mechanic to handle this fix. Without a service manual, this job is beyond the scope of the average diy’er I expect. The vehicle-specific scan tool can probably turn on and off the individual parts of the circuit, making it easier for your mechanic to find the source of the problem quickly.

You might find this to be of use for various reasons:

You will also end up needing pinouts for it if you’re looking to check stuff with a meter.

I saw that video. It is helpful. I’m going to check the connectors and possibly pull it out o make sure it is not rusted through. Since I am also having other weird issues like parts of the LCD of the fuel gauge not displaying in colder weather and radio intermittently cutting gout. Sounds like a connection issue. At one point, the closing of the passenger door corrected the LCD issue for short time. I think It may be wiring related for this sensor too since I replaced it. Thanks for all the info so far. I will update when I get a change to check the wiring.

If you replaced the EVAP system purge valve for this code, you replaced the wrong part.

You need to replace EVAP system vent solenoid.


That was the part I replaced except I used the dorman part. I cleared the codes and it came back pretty quick. Based on the video , I might pull and check the ECM or at least it’s connection to make sure it is not rusted through.

This fix will require advanced diagnosis as it may lead to a faulty engine computer and even a water damage repair if the PCM has visible signs of water in it.

You can check for power at the valve with key on and check the ground wire back to the PCM and beyond that it’s time to think about the PCM itself not being able to ground the vent valve.

Ok. I checked all connections with no luck. I decided to check the ECM and the pictures in the link below are of my ECM. I am going to see if Nissan will budge.!25395&authkey=!AF1ajIPRmsiaKo8&ithint=folder%2c.jpg

Youch. That’s about all I’ve got on that.

That is the part I replaced, just used the dorman part.

That is the part I replaced, just used the dorman part.