P0456 Small Evap Leak

Hello Everyone,

Picked up this vehicle a few weeks back now, and I knew it had this code when I got it. I figured it was the gas cap like it almost always is from my research. Bought a new factory gas cap and have been driving it around for a while since then and the light has not gone off (from my research it should go off after it's been fixed).

I've looked over the hoses and they all appear to be connected. The ones related to the purge valve under the cover are in "decent" condition. I wouldn't say they are perfect obviously, but there's no cracks.

I went under and looked at the charcoal canister hoses and it seemed to be fine from what I could see.

So I bought a techstream cable and ran the "Evap Test" in the utilities and got a "flag" at Time/Frame : 00.02.109 / 5

I have no idea what Techstream was testing at that point in time when it created this flag.

Any tips on what I should be doing or what Techstream was doing at this point in time?

 

Bump... anyone with thoughts or next steps other than throw money at it and replace things?

 

first off what code did you get?
If you bought this used and are unsure if any mods were done with the intake more specifically, I would look up the evap hose routing under the hood, or online and see if the hoses are routed correctly. If they're then try pushing those hoses all the way in. Sometimes they slide out a bit, another thing you could do is just clear the code and see if it comes back at all. Hope this helps some

 

The code is P0456.

The truck was purchased from my mom, and I have the service records with everything done at the dealership. She said it started throwing a code maybe a year ago, but she's only driven it 4,000 miles in the past 5 years. She didn't look into it at all, as I said I would deal with it when it got out here. I've already checked the lines going to the purge valve / charcoal cannister at least and they were fine. I did a quick overall look at all the other hoses I could see easily, but there could have been one I missed.

I'll double check them again then.

 

Have you tried clearing the code and see if it returns?

 

It was cleared once before it shipped out here because the battery was dead and they swapped in a new one.

After adding the new gas cap, no. I guess it wouldn't hurt. I just read online from others that it went away eventually. Also figured that since I ran the EVAP Test in Techstream and it found a "flag" that there really was something still wrong?

 

Make sure when you fill it up, not to add any more after the pump clicks off. That’s a great way to destroy your charcoal canister

 

So I cleared the code, replaced the PCV (read it's just a good thing to replace occasionally). I didn't spot any hoses loose, but I took pics (below) of the engine bay overall and maybe someone else will spot something? Obviously haven't received a code back yet, but I will update the thread in a few days if it comes back or not.

 

I’ve had this same code on another vehicle and the EVAP purge valve was dirty. If the code comes back, might be worth cleaning.

 

I was chasing a combination P0441 and P0456 codes. Mainly 0441 with the occasional 0456 to sweeten the deal. I went through the usual - OEM gas cap, replaced the purge VSV, also
the evap hose from the purge valve to the hard line heading to the rear because I didn't like the looks of the internal cracks. No joy. So I bit the bullet and bought a smoke generator
from Amazon for about $125 (cheaper than I was quoted for a smoke test locally). Long story short I found a leak in the fuel filler pipe that I never would have without the smoke.
Changed that out and my codes cleared.. for a while but just back to 0441. So then I picked up a copy of techstream and a VXdiag nano dongle and manually commanded the evap valves to
cycle, where I discovered that the connector on the purge valve was flaky/intermittently not making contact.. I was able to temporarily zip tie the connector to the evap hose in such a
way as to force proper contact, and my issues resolved. No CEL for the week it took me to get the replacement connector, and none since I replaced it.
Smoke is your friend.

 

I'll provide a little update...

Reset code on Friday 5/12, drove about 120-130 miles that weekend (half of it towing a ~4500lb boat). Filled up gas on Sunday. Drove it around a bit earlier in the week. Since then it hasn't moved too much. CEL is still off. I ran a I/M Test (iirc that's what it's called on the scan tool) and it said EVAP System Passed.

So I may be in the clear, I don't know for sure. So if anyone is running this issue, clear the code after you replace the gas cap as it wasn't going away for me. Will update if it comes back.

 

CEL came back on Friday with the same code, 0456. So I guess it wasn't the gas cap as hoped.

It was gone for about a month and about 1k miles.

 

Hey Tenny, just curious if you figured out what was causing 0456?

 

There’s more post about this in another thread you can search my posts to see all the details.

I replaced both purge valves and it came back once after that but hasn’t come back since.

I don’t drive the truck very often now as I got a Tesla Y Performance. So the truck is only used for truck duties like carrying stuff and launching the boat. So I don’t know if it’s 100% fixed or just not driven enough to expose the problem again.

 

Buy a Smoke Machine and forget guessing.... I guessed too many times and I just hooked up a smoke machine and the fuel vent line is leaking due to a bad clamp