I took my fuel cap off this morning and heard the whoosh again, but still could not tell if it was pressure or vacuum. I left the cap off and drove 10 miles to work, with the MIL coming on about 70% to 80% of the way there. It was a P1457 so I captured the available data and reset the codes. I also re-installed the fuel cap. It is strange that it took longer to get this MIL indication than anytime since I changed the two-way valve.

Later in the day I drove home. I checked for pending codes and did not have any. I will keep an eye on this and hope for the best, but I expect I will get a pending P1457 code tomorrow, and maybe even a MIL by the time I get home

 

I tested the canister again (had done so several weeks or maybe a month earlier). I set this up with rubber plugs stopping all the canister holes except the vacuum source which I attached to a hand held vacuum pump. This time it held 10 InHg for over half an hour. (See first attached picture.)

I connected 12V to the canister vent solenoid with the rubber plug still in the canister vent solenoid outlet. I heard the solenoid click when power was applied but that did not change the 10 InHg. (See second attached picture.)

With the 12V connected I removed the rubber plug from the canister vent solenoid outlet. To my surprise, that did not change the 10 InHg. (See third attached picture.)

I was surprised because earlier testing a few weeks ago of this same set of parts being testing using the same tools I had slightly different results. In the earlier testing I used 15 InHg but with the 12V applied, when I removed the rubber plug the vacuum dropped to around 8 InHg. The 9/21/2018 test used 10 InHg but it held with the 12V applied and rubber plug removed. Since the 10 InHg held, I tried to increase the vacuum. I could pump it to around 12 InHg but now it would slowly drop to around 7 or 8 InHg before it would hold. This could be modeling what is going on while driving; the canister vent valve is closed while the manifold vacuum is applied, and there is no rubber plug to help hold vacuum. I think this likely suggests an internal leak. I was able to repeat pumping up the vacuum without the rubber plug in place, and it again slowly (seemed like less than 30 seconds) dropped to around 7 or 8 InHg. (See fourth attached picture.)


I had intended to next apply pressure (the hand held pump can generate vacuum or pressure depending on a valve setting) and use soap bubbles to test the canister vent solenoid, but I actually forgot to perform that test. Since on the same day I received a new (after market, not a genuine Honda part) canister vent valve, I went ahead and replaced the one that appeared to be leaking based on testing above. (See fifth attached picture, new part installed, old part next to canister.)

Test driving has been so far so good. I have driven it quite a bit, at least 35 40 miles, and do not have a MIL. However, I have had a pending P1457, and am wondering how long it will take for that to either become confirmed or cleared. I will say that prior to replacing the canister vent solenoid valve, the P1457 with the [check engine light] MIL was a lot easier to produce, so things do seem better in any case. Similarly, when I recently replaced the two-way valve, I stopped getting P1456 and started getting P1457. The response was immediate and different from what I had seen a long period of time (months).

I have slightly less than half a tank of fuel at this point. If I get through that and the next tank of gas without a MIL, I will consider this fixed. I am hopeful, but still have that pending P1457.

 

Sadly the P1457 has returned. So far I have replaced the gas cap, two-way valve and canister vent solenoid, at separate times but in that order. Originally I had a P1456, but since replacing the two-way valve I have had P1457. I am going to try replacing the two-way valve bypass solenoid. It is a moving part and many people recommended replacing it when replacing the two-way valve.

I noticed that code detections almost always occur in the morning on the first drive of the day. Perhaps test driving right after replacing a part will not reproduce the drive cycle conditions needed as well as my morning drive.

 

I have attached pictures of the next part to be replaced, the evap bypass solenoid.

 

When you are replacing evap parts on a Honda (which is real sensitive) you want to use Honda parts. I've been there and done that with a 12 Accord. Turned out the car I was working on didn't like anything but what came on it. The car issue was the solenoid with tube.

 

Which solenoid? The bypass solenoid?

I am biased in favor of using genuine Honda parts. This is an old car and I have found some of the after market parts can be significantly less expensive. The advice is appreciated, but I've gone forward with yet another after market part, as addressed in my prior and next post.

 

I spent quite a long time trying to to locate the cause of the original problem, P1465. On 9/13/18, I decided to try replacing the two-way valve. I removed the old two-way valve and initially thought both O-rings had been missing between the original two-way valve and the original bypass solenoid. Since the new two-way valve came with both O-rings, I installed those with the new valve. After replacing the two-way valve, I found the original larger O-ring on the floor, so it must have fallen off while I was doing the job. The P1456 went away after replacing the two-way valve, but then I started getting P1457.

I found the original smaller O-ring, today, 9/24/18. It was inside the bypass solenoid, along with the new one that I had installed when replacing the two-way valve. That is a workmanship issue. I suspect the P1457 problem may be related to having two small O-rings installed where I should have installed one.

In the first couple pictures you can see the old two-way valve. It has some oil and dirt on it and it is sitting on a piece of tan cardboard. One of the pictures shows the original large O-ring installed on the lower horizontal opening but without the small O-ring on the horizontal opening just above that. The long vertical fitting is where a vacuum hose that leads to the tank pressure sensor is installed.

In the second couple of pictures you can see how the new two-way valve was improperly installed (because there were two of the smaller O-rings where there should have been one) onto the bypass solenoid. The additional small O-ring causes an uneven gap between the bypass solenoid and the two-way valve. Since (on 9/13/18) I replaced the two-way valve while the bypass solenoid was still installed on the car, I could not see this poor fit.

In the third pair of pictures you can see how the new two-way valve is installed on the new bypass solenoid, with the two O-rings where they should be, and no extra O-rings installed. I temporarily applied 12V to the new bypass solenoid during installation, as the air seal was otherwise making it difficult to get the small O-ring on the two-way valve inserted into the bypass solenoid.

I cleared the pending P1457. I have since driven this about 15 miles, with no pending codes so far. The car has about a quarter of a tank of gas remaining. I plan to drive it some more today, and then in the morning the way it was driven when codes were previously detected.

Replacing the gas cap on 6/30/18 did not fix the original P1456. I tested the canister itself for leaks on 8/25/18 and did not find any. The old two-way valve had fuel in it when I replaced it on 9/13/18. Replacing the two-way valve on 9/13/18 stopped the P1456 but started the P1457.

I again tested the canister itself for leaks 9/22/18. The only indication that there might be a leak was related to the canister vent shut valve. I replaced the canister vent shut valve on 9/22/18 but still had P1457.

The new two-way valve did not have fuel in it when I replaced the bypass solenoid on 9/24/18. Testing is now in progress.

Original two-way valve (above).

Original two-way valve with large O-ring on bottom horizontal opening (above).

Improperly installed connection between two-way valve and evap bypass solenoid (above).

Improperly installed connection between two-way valve and evap bypass solenoid. Gap is larger at top than bottom of connection (above).

New two-way valve with new evap bypass solenoid installed (above).

New two-way valve with new evap bypass solenoid installed. Gap between two-way valve and bypass solenoid is more even (above).

 

Seanjordan20's 09-24-2018 post seems worth repeating:
I had a confirmed P1457 this morning (9/26/18). I took the canister off, plugged holes, pumped in a little air pressure and found that it would not hold that pressure, and if I listened carefully I could hear air escaping. I sprayed soapy water where the recently installed canister vent solenoid attaches to the canister and got bubbles, so I found a leak. The WVE/AIRTEX/WELLS (WVE 2N1136) canister vent valve / solenoid is something I installed when I recently started getting P1457. My prior canister leak testing (8/25/18 and 9/22/18) was based on vacuum rather than positive air pressure, and I had not used soap bubbles. The prior testing also used the original DENSO part. I never previously tested the new RockAuto recommended part when installed on the canister.

I suspected the canister vent valve / solenoid based on web searches for "Accord P1457". I now think the initial P1457 was actually due to the second small O-ring unintentionally installed when I replaced the two-way valve. There should be one large O-ring (which I had) and one small O-ring (but I had two) between the two-way valve and the bypass solenoid. The P1456 went away with the removed/replaced two-way valve, and the P1457 showed up after the new two-way valve was installed.

Web searches led me to suspect the canister vent valve / solenoid, but the part recommended by RockAuto for my car was either defective or would have never fit in the first place. Either way they will not refund my money since I had installed the part. I re-installed the DENSO canister vent valve / solenoid that came installed on my car from the factory, as the extra, second small O-ring (between two-way and bypass solenoid) seems like the original P1457 problem. The new part from RockAuto clearly leaks (see photo evidence) and it is disappointing to learn that they do not stand behind what they sell, but the $35 tuition taught me a lifetime lesson to shop elsewhere in the future.

Recap: The initial P1456 problem appears to have been caused by a failed two-way valve. The P1456 has not been reported since the two-way valve was replaced. P1457 showed up just after two-way valve was replaced, and I now suspect that was due to two small O-rings (I did not notice there was already one inside the bypass solenoid) where I should have had one. Before detecting the extra O-ring, I replaced the canister vent valve / solenoid, but the replacement part was either not the right part to begin with or it leaked well within warranty. The part seller could not care less. I re-installed the original DENSO canister vent valve / solenoid. Test driving so far indicates Evap System Monitoring is not continuous but is available on my car, and that testing completed. There are no pending codes and no confirmed codes. Furthermore the Mode $06 CID $01 TID $2E now has a value of 41 with a minimum of 8 needed to pass, which I have never seen since I started tracking when I got the P1457. As far as I can tell, that mode $06 info refers to EVAP_PCT, which is the duty cycle applied to the purge control solenoid, and the 41 would indicate the valve is activated 41% of the time.

I have what appears to be some encouraging news, but will continue to test, particularly in the morning when setting pending P1457 codes or confirming them has become quite predictable.

 

It sucks they would not take the part back but look on he bright side it was $35 versus $200. Glad you have gotten somewhere with this and hopefully you are in the clear.

 

I agree that it could have been a more significant loss, and appreciate the hope that the P1457 is in the past.

I sent email to service@rockauto.com regarding the defective part. They replied in a timely manner and provided instructions to return the part for a refund.