Codes P0440 and P0446

Tiny
YOURMINKY
  • MEMBER
  • 1997 NISSAN SENTRA
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 156,000 MILES
My car is giving P0440 and P0446 MIL codes together, which means large EVAP leak. I cleared the ECM codes, but they keep coming back after a while.
The car runs fine, starts fine, no issues otherwise.
I read this can be caused by the following:
Bad gas cap, intake manifold hairline crack, bad hose, cracked charcoal canister, EVAP vent control valve solenoid not closing properly, bad EVAP canister purge valve.
I checked the usual suspects and I'm down to 3 possibilities, the charcoal canister, the EVAP vent valve/solenoid, the EVAP purge valve/solenoid.
YouTube doesn't have any videos for replacing the canister or the vent valve for this model.
What could be causing this issue? What tests to perform to narrow down possibilities? Which item should I replace first? Is there any way to fix the parts other than buying brand new replacements?
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Thursday, August 1st, 2019 AT 9:30 PM

40 Replies

Tiny
SCWICKEDSTANG
  • EXPERT
Hello,

In the diagrams down below I have included the factory diagnostic troubleshooting guide for DTC P0446 for your vehicle. The instructions call for doing this DTC first. In order to go through this guide correctly you will need to have a vacuum pump, a multimeter, and a scan tool with PID capabilities. Please go through this guide and get back to us with what you are able to find out.

Thanks,
Alex
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Friday, August 2nd, 2019 AT 9:04 AM
Tiny
YOURMINKY
  • MEMBER
Your help is greatly appreciated. I have several questions.
1. Thanks for the 14 images. Which test should I perform first, the vent valve(solenoid) test or the pressure sensor test?
2. What does the 'without consult' photo (2nd row, 2nd photo) mean?
3. What does NG' mean?
4. I am handy with a multi-meter and I also have a Bluetooth DTC scan-tool with PID capabilities. You mentioned I need a DTC tool with PID. Is that just for finding the actual DTC codes? If yes, I already found the codes and they are P0440 and P0446 together. If not, please explain.
5. When it says "ignition switch on", I will not crank or start the engine first, right?
6. Where is the EVAP control system pressure sensor located?
7. I don t have a vacuum pump. Can I attach a pipe and blow and suck air?
8. I checked the fuse bank located at bottom-left of the steering. There was no fuse for the EVAP system. Do these EVAP solenoids have fuses? Where are they located? Can it be a fuse issue?
9. What is the proper resistance in ohms for the vent solenoid coil and the pressure sensor?
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Friday, August 2nd, 2019 AT 2:26 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

1) Diagram #8 gives you the order to test in.
2) Consult is the name that Nissan gave to it's factory version of a scan tool that is used by their technicians at the dealership.
3) Negative or No Go, take your pick.
4) No. It is for accessing the EVAP Monitor information and turning the Monitors ON/OFF.
5) No, that is "start", in this case on is "RUN", the position right before "start".
6) On the left rear underside of your vehicle.
7) No. They are available for just a refundable deposit at parts stores like AutoZone. You have to have a gauge for measurement, which the vacuum pump does.
8) No. Power and Ground provided by the Power-train Control Module(PCM).
9) I do not have the information available at this time. The coil just uses electricity provided by the PCM to move a plunger back and forth to allow vapor gases to pass. The more electricity the more plunger movement, so resistance here would be very low. The pressure sensor is probably different, but, like I said, I do not have that information available right now.

Thanks,
Alex
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Friday, August 2nd, 2019 AT 8:13 PM
Tiny
YOURMINKY
  • MEMBER
Thanks for the clarification.
I am using the Torque Pro app on my Android as the scan-tool to read the OBD information using Bluetooth. I am not sure whether the Torque Pro app can send/receive commands for turning on/off EVAP monitors.
I did some testing as you suggested and I think I found the issue.
When the key is on/run position (engine not started) I get 11.2 to 11.6 volt at the EVAP vent valve solenoid, so the wire harness is good.
The solenoid coil shows around 11.5 ohms resistance, but does not make any sound when energized.
I connected the solenoid to a regular 9 volt battery and then a 12 volt car battery but I did not hear any ticking sound of the plunger moving/closing/opening in either case. Shouldn't there be an audible tick sound from the plunger when energized?
Is there any way to repair the vent valve solenoid?
Please see the photo and let me know if that is the EVAP control system pressure sensor.
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Friday, August 2nd, 2019 AT 10:11 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

Yes. The Vent Valve Solenoid should either be off or on and when energized you should here a click. The best thing to do here is just replace the solenoid. If you want to double check just to make sure. Run a voltage drop test on the circuit. This is the preferred way to check electrical circuits and will tell you where the bad segment of the circuit is with amazing clarity, revealing damaged segments you would never be able to find running continuity tests with the multi-meter in Ohms (Resistance) setting. Please go through the guide and get back to us with what you are able to figure out.

Thanks,
Alex
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Saturday, August 3rd, 2019 AT 3:17 AM
Tiny
YOURMINKY
  • MEMBER
One of the bolt's head snapped. I was able to remove the EVAP vent solenoid but the broken bolt's anchor which is embedded inside the charcoal canister also broke and now rotating freely and I cannot remove it. A photo is attached. Any suggestions?
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Saturday, August 3rd, 2019 AT 4:51 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

If it were me, I would get a Dremmel tool, and wearing safety glasses with side shields, I would grind the head of the bolt off. That way I could pull the charcoal canister off, and then extract the bolt shank and replace the bolt with a new one when I went to reinstall the charcoal canister. Please keep us informed.

P.S. I love your screen name.

Thanks,
Alex
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Saturday, August 3rd, 2019 AT 5:04 PM
Tiny
YOURMINKY
  • MEMBER
The bolt shank won't come off that way because I think there is a captive nut on the other side. And the captive nut has broken free from its moorings. The whole thing now rotates freely. Here is a close-up of the bolt with broken head and shank and free from moorings.
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Saturday, August 3rd, 2019 AT 6:00 PM
Tiny
YOURMINKY
  • MEMBER
I am thinking about either using a Dremmel tool and cut off the broken shaft with the captive nut attached or yank it out. Which one do you suggest?
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Saturday, August 3rd, 2019 AT 9:15 PM
Tiny
YOURMINKY
  • MEMBER
Here are bunch of photos with clear descriptions that may help understand the situation.
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Saturday, August 3rd, 2019 AT 9:17 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

I understand what is going on. If the whole bolt rotates around and it is broken on the side of the head, you should be able to just pull the whole bolt through the hole on the charcoal canister. If that isn't possible, then I would grind the head of the broken bolt off with a Dremmel tool and a grinding wheel. Once the head of the bolt is off the EVAP Vent Solenoid should come right off, then you can see whats going on with the shank and address it better because you will better access to it. Please keep us informed.

Thanks,
Alex
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Sunday, August 4th, 2019 AT 3:25 AM
Tiny
YOURMINKY
  • MEMBER
I greatly appreciate your responses.
The charcoal canister fasteners are in bad shape, full of rust. They will probably snap if I try to take the canister off.
The solenoid does have a stub with an O-ring that goes inside the canister and seals. A photo is attached.
I was able to remove the old solenoid and clean it and put it back. I am using a green coat-hanger wire to secure the old solenoid with the canister. See photo. The old solenoid is clicking and sealing after cleaning with PB Blaster. I only did a mouth-blow-air and suck-air test.
The car drove fine last night. I will replace the old solenoid with the new solenoid when I have a plan to attach it properly with the canister and I need your help.
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Sunday, August 4th, 2019 AT 8:59 AM
Tiny
YOURMINKY
  • MEMBER
I drove the car on the interstate and now only the P0440 code comes on since the old solenoid is 95% air tight, leaking air either through the rusty valve seal inside the solenoid or the O-ring didn't seal since it is only held by 1 bolt and a coat-hanger wire.
I am thinking about putting a thin layer of RTV as gasket on the mating surfaces of the new solenoid and the canister and hold it with the 1 good bolt and the coat-hanger. Good or bad idea?
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Sunday, August 4th, 2019 AT 4:34 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

The RTV sounds like a great idea. Many gaskets have been made this way. I personally have put an entire engine together using red RTV for every gasket, save the head and exhaust manifold gaskets. The wire coat hanger, on the other hand, is a horrible idea. What is the issue you are having with the bolt/bolt hole there?

Thanks,
Alex
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Monday, August 5th, 2019 AT 1:24 AM
Tiny
YOURMINKY
  • MEMBER
I am thinking about JB Welding a captive nut and using RTV around the mating surface. However, the old captive nut along with the broken stem/shaft are not coming off of the canister. I don't want to force it out and crack the canister.
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Monday, August 5th, 2019 AT 8:50 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

Okay, can you use a Dremmel, again, and a cut off the shank of the bolt, drill the captive nut, tap it, JB Weld it in place and the put a new bolt in place? If this is too much, I would at least use black zip ties to secure the EVAP Vent Solenoid in place. They will work better and look better as well. When using zip ties it's a good attedge that 2 are 1 and 1 is none. Please let us know how it turns out.

Thanks,
Alex
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Monday, August 5th, 2019 AT 9:30 PM
Tiny
YOURMINKY
  • MEMBER
Can you please recommend the type of RTV and JB Plastic Weld I should buy? I went to the store today and there were dozens of options. People recommended the quick set JB Weld epoxy or superglue gel with baking soda. I have plastic cement, will it work in this case?
Should I insert an upside-down bolt in the cavity where the captive nut would go (please see the stock photo below) and use it as a post to attach the solenoid with another nut Or use a regular captive nut and put a glob of JB Weld around it like it used to be?
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Tuesday, August 6th, 2019 AT 5:44 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

There is no real wrong answer here. If it were me, I would take out broken piece and put a bolt in, JB Weld it with regular two part epoxy JB Weld and use a matching nut to fasten everything down. In the end though, all you are doing is fastening down the solenoid. Remember, there is more than one way to skin a cat. As long as the solenoid gets fastened to the canister, then that was the right way to do it. As far as the RTV goes, really any of them will work on this application. I would go ahead and use the black, just because all of parts you are working with, the charcoal canister and the solenoid are black as well. Please keep us informed.

Thanks,
Alex
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Tuesday, August 6th, 2019 AT 8:01 PM
Tiny
YOURMINKY
  • MEMBER
The old car's exhaust is making loud noise as of tonight. It is very rusty and there is a big hole in the tailpipe in the front side - the part that comes out of the engine. The car is not accelerating properly anymore. Shaking when trying to go faster. It is giving 3 total fault codes now. P0440, P0136 and P1441.
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Tuesday, August 6th, 2019 AT 8:47 PM
Tiny
SCWICKEDSTANG
  • EXPERT
Hello again,

Okay, so DTC P0440 we know is an EVAP leak, and that is getting fixed. So let's take a look at the other two DTC's, and see what we got. In the diagrams down below I have included the factory diagnostic troubleshooting guides for DTC's P0136 and P1441. The exhaust manifold just unbolts. The bolts are usually rusty and baked in place, and can be a bear to break loose. Get a can of PB Blaster or WD40 and soak the bolts liberally and let soak overnight before attempting to break them loose. Go through these guides and get back to us with what you are able to find out.

Thanks,
Alex
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Wednesday, August 7th, 2019 AT 12:04 AM

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