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-   -   PO406 Code (http://www.jeepgarage.org/f107/po406-code-63779.html)

nek121328 08-06-2013 07:38 PM

PO406 Code
 
Fired up the 2011 WK2 with the 5.7L this afternoon and observed the check engine light. Stopped by the closest parts store and PO406 Evaporate Small Leak was the shown. Remove the gas cap and removed the rust build up on the filler neck. Then cleaned the gasket on the cap itself. The indicator is still illuminated. I may have missed an earlier post, but has anyone encountered the same situation?

The Evil Twin 08-06-2013 08:58 PM

Re: PO406 Code
 
It can take several engine cycles for the code to clear (start, run to operating temp, shut off). Same thing happened to me when I neglected to tighten the cap. I would wait a few cycles to see.

nek121328 08-07-2013 07:53 PM

Re: PO406 Code
 
After several lengthy bouts of operation today, the Check Engine Light is still illuminated.

The Evil Twin 08-08-2013 04:41 PM

Re: PO406 Code
 
Hmmm.. interesting. Long explanation aside, this usually means that the ESIM (or current version thereof) failed to detect a pressure change in the Evaporative Emissions System. What it is looking for is for system pressure to go down in proportion to temperature. In a sealed system, a decrease in temp = proportional decrease in pressure. If the system is no longer sealed then pressure would remain steady (relatively).
My $0.02- have the code reset. It may never come back. If it does, then you might need to have someone test the sensor and/ or do a pressure test of the system to determine the leak. If anyone has been under the hood lately I would vheck the obvious vacuum lines and vacuum plugs to make sure they are in place and secure.

AAAA 08-09-2013 09:25 AM

Re: PO406 Code
 
Whoa. You said rust on the filler neck. That can't be good.

nek121328 08-09-2013 04:43 PM

Re: PO406 Code
 
There was rust build up on the sealing lip of the filler tube. I know the cap is always tightened after removal. Sounds like a trip to the local dealership for the code and the transmission software update this week.

nek121328 08-11-2013 09:57 PM

Re: PO406 Code
 
Approximately 500 miles later and the Check Engine Light is no longer illuminated.

tomk 08-12-2013 04:31 AM

Re: PO406 Code
 
The leak detect system (NVLD, I don't have a WK2 FSM to verify) uses the vacuum created when the ambient air cools down at night to check for leaks. So it may take days or weeks to clear depending on the weather in your area.. certainly at least an overnight.


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