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P0456 and U0019 on 09 4.7 WK?

6K views 8 replies 4 participants last post by  ITsTEXnical 
#1 ·
Engine light came on so I checked with my flashpaq. P0456 Evap system leak and U0019 Can B Bus. Checked the gas cap it was on tight. Could cap be bad. What could be cause of can b bus code? I cleared just wait to see if they come back. Any ideas appreciated.
 
#2 ·
I've been fighting evap leaks on my 09 4.7 for a while now I pulled codes twice first one was a very small leak, checked everything found nothing cleared code and it never came back. Came on again 6 months later as a very large leak just cleared it right away and hasn't came back on since that was a month ago, I can't understand what causes them but i know it's not much to worry about. As long as the code stays clear
 
#3 ·
Cleared code last week just came back tonight. Might change gas cap to see if that's it. Thanks
 
#5 ·
An evap leak is just that, a leak in the evap system. There are integrity monitors to ensure the evap system is not leaking HC's to the atmosphere. The most common problem if you want to talk pattern failures, would be the ESIM switch, it is mounted on the charcoal canister. This is the switch that tells the PCM if there is a leak or not, and it is not uncommon to give false information when it fails. There are also a number of hoses near the charcoal canister worth inspecting. IIRC the assembly and lines are mostly behind the rear drivers side wheel, most easily accessed with the removal of the rear bumper cover.
 
#9 ·
Same issue, bought an aftermarket ESIM. Fixed the problem but code kept popping up. Turns out the replacement didn't include a small rubber ring that goes between the new evap pump/switch and the charcoal canister. Lucky I saved the old ring after finding it on the ground. Fit exactly, code permanently gone.
 
#7 ·
Figured I would order a new gas cap from just for jeeps just to see if that was it. I order it go to leave 5 minutes later and light goes off. I'll just keep waiting to see if it comes back on
 
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