I've had this CEL code P0455 come on at least 7 times now. It only stays on for about 1-3 days and then turns off for 3-10 weeks at a time.

P0455 - Gross/Major EVAP Leak.

I took my car to a Nissan service shop and they visually inspected all of the fuel lines, hoses, the evap valve, and cannister. Everything looked good. They hooked it up to a smoke machine and there were no leaks after two times running the test backward and forward.

I am getting a bit angry that this keeps coming on, it's going to mess with my emissions testing for sure.

Any ideas what to look for? The shop that looked at it specializes in Z-cars and I know the owner personally and he's quite familiar around the VQ.

Edit: Forgot to mention, I replaced the fuel cap already

 

did you check for CMDTCS and ODDTCS? your issue could be a ODDTC...

 

I have no idea what those are

 

what kind of gas are you using. ethanol in the gas has been the culprit of some evap codes that have been coming up more frequently as of late. ive seen friends spend 100s of dollars chasing evap. from what I hear it controls fuel pressure at start up, but not effected enough to not have the vehicle start

 

Yeah I see no difference in the performance of my car with or without the CEL on/off. I don't smell gasoline while driving either. I put in the standard 93 octane premium fuel, typically from exxon stations. I believe they use the standard up to 10% ethanol.

 

ODDTCS are on demand DTC's there codes that are happening right now. CMDTCs are continuously monitored DTC's that happen all the time. Talk to ur shop to check for both. If ur car wasn't being driven while a scanner was hooked up ODDTCS won't show.

 

I could never get the car to the shop with the light on. by the time id call in and have time to drop it off, the light has gone off. he did see a history of all the codes and nothing led him to any conclusions unfortunately.

 

I had that problem until I learned how to really close my gas cap, I even replaced mine but until I started getting it to click about 6 times p0455 would come and go.

 

When the gas cap clicks, doesn't that mean the cap is fully tightened, thus it clicks and does not turn any further, similar to a torque wrench?

 

Yeah I get that code occasionally and noticed that's the culprit is the gas cap. My filler neck is slightly rusty so I think the seal isn't always perfect. As long as I always put the cap on with the same side up (while looking at the white portion because the black part turns separately) then it seals fine and I don't get the code.

 

I've been getting this code periodically also. Sometimes it clears itself, sometimes I clear it myself and it wont come on for weeks. I use Shell 93 and have only used Shell for the past 4 years. It seems to trigger the SES light right after driving on a rough road, over rough railroad crossings, etc. I had this code appear under warranty and they replaced the canister, but that was a few years ago.

I do notice a little rust near the filler neck, so maybe my cap is not sealing good enough?

 

Food for thought, and I'm not suggesting you throw money at a problem without knowing what the problem really is... The canister purge valve sometimes sticks "open" on G's, which will throw a P0455. It's a quick, easy, inexpensive fix. But you're only fixing the SES light. Typically, 0455 code is emissions only, nothing terrible is going to happen if you don't fix it right away. (I'm no mechanic, btw, just throwing it out there for discussion).

 

Yeah I am not too worried about my car being damaged by this problem, as it runs perfect, no idle issues, same gas mileage as always, but I do have to pass emissions yearly so it does concern me there. It's been getting a bit worse lately, as in it comes on more frequently and stays on longer. Hopefully next time I bring it in, it will actually be on so that maybe they can find what is wrong.

 

Again, not suggesting you throw money at something you're not 100% positive about, but if you really have $40 burning a hole in your pocket, and 10 minutes to spare, it's an easy fix. I had to drop my entire canister, only because the "teeth" on my canister were a bit chewed up. Anyway, about 20 miles after replacing my valve, my SES went off. Replaced mine about 2 months ago (?) and no return 0455.

 

From what I've read, that is a common cause to this problem. What concerns me is that the guy I took it to said he specifically tested the valve and it worked as it should. I guess that doesn't necessarily mean that it works ALL the time though.