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2003 ML350, Trabant P60, VWJetta, BMWG650GS
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269 Posts
Discussion Starter #1
'hooked up an Actron scanner to my car and got one error code that said:

P0456
Evap. Emission Control sys
Leak very small

The check Engine light or any other light were not on at the time, I was just fooling around with the scanner. Reset the error and few hours letter checked it again, there were no errors.

My friend, who gave me the scanner, shook his head and said.:"..why they would put a sensor for that in there, I don't understand". He's been working in his father shop since he was a 15 but would not know how to troubleshoot this one because does not know where exactly to look for it.

Could anybody tell me what the repair manual says about this error and where's the bloody hose is so I can look it up and fix it?

Thank you.
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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11,146 Posts
Probably a bad gas cap. If the leak gets more pronounced, it WILL throw the CEL.
 

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Premium Member
02 ML320 06 ML500
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17,044 Posts
Code 456 relates to the Purge Control Valve, which is located next to the master cylinder/brake booster. Small leaks usually occur in the hoses going to the valve. See the photo in the pdf, the valve is marked Y58/1, and inspect the hoses for cracks.

If the code reappears you might have to have the evaporative emission system filled with smoke to determine the location of the leak.

Remember that the code is for a small leak, so do not replace the valve. Leaks are always at the plumbing/hoses.
 

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Registered
2003 ML350, Trabant P60, VWJetta, BMWG650GS
Joined
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269 Posts
Discussion Starter #4
Thanks guys,

Always great help.

I'll check both, the O-ring from the Gas Cap and the hoses going to and out of the Purge Control Valve.

As a paranthesis, is the Evaporative Emission System what takes the gas vapors that form inside the Gas Tank and then pumps them into fuel injectors? And what is the role of the Purge Control Valve... This for my own education
 

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Premium Member
02 ML320 06 ML500
Joined
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17,044 Posts
Thanks guys,

Always great help.

I'll check both, the O-ring from the Gas Cap and the hoses going to and out of the Purge Control Valve.

As a paranthesis, is the Evaporative Emission System what takes the gas vapors that form inside the Gas Tank and then pumps them into fuel injectors? And what is the role of the Purge Control Valve... This for my own education
Yes you are correct, but it is directed back to the intake manifold.

You will have to find an independent mechanic who has a SMOKE MACHINE. With it, when properly used, leaks the size of pin holes can be found. Again, remember that it is not the valve, but the hoses that are the problem, one of which runs the full length of the truck all the way back to the charcoal canister.
 
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