Intermittent P0456

[gimlithepirate]

I've got the P0456 check engine light, but its not being consistent about it.

I've replaced the gas cap (because that is 100% where you should start), and the issue has persisted.

Finally setup my techstream tool and decided to watch the evap pressure levels... but it passed the evap test when triggered from techstream!

This is happening about once every other week. When it happens, I reset the code (so I get VSC, etc. back)... and then there is no issue for another couple of weeks.

Any suggestions? Best I've got right now is to keep resetting the code until its consistent so I can tackle the problem.

 

[AuSeeker]

I've got the P0456 check engine light, but its not being consistent about it.

I've replaced the gas cap (because that is 100% where you should start), and the issue has persisted.

Finally setup my techstream tool and decided to watch the evap pressure levels... but it passed the evap test when triggered from techstream!

This is happening about once every other week. When it happens, I reset the code (so I get VSC, etc. back)... and then there is no issue for another couple of weeks.

Any suggestions? Best I've got right now is to keep resetting the code until its consistent so I can tackle the problem.

Did you replace the gas cap with OEM?

 

[Runnin on E]

Not sure what engine you have but the 2UZ manual section describing in detail the evap system is ES-419 to ES-453. There is a lot of really good trouble shooting info and system component checks in there. Here is a shot of the first page.

 

[gimlithepirate]

Oh I was looking for those pages. Have to step through it.

 

[VA984Runner]

intermittent P0456

I had the same problem on a Gen 3 V-6 4Runner last summer and never found any problem. I replaced the gas cap with an OEM cap and the problem reappeared every two weeks or so. The problem stopped last fall as temperatures cooled off and has not reappeared since. My conclusion is that the problem may be temperature dependent.