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600 coupe, one of the very first built
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Purge (MOT) valves can be cleaned. Take a 9V battery and apply to the connector.
There should be an audible click and you can spray carb cleaner fluid into the opening.
Do it a couple of times.
If no click, the solenoid is dead and the valve stuck.
 

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Discussion Starter #3
Purge (MOT) valves can be cleaned. Take a 9V battery and apply to the connector.
There should be an audible click and you can spray carb cleaner fluid into the opening.
Do it a couple of times.
If no click, the solenoid is dead and the valve stuck.
I meant the valve on the evap canister. I’ve already replaced the solenoid because the plastic housing was falling apart thanks for reading
 

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600 coupe, one of the very first built
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63 Posts
I meant the valve on the evap canister.
This must be an add-on for the OBD-2 compliant cars. Mine is an early model and has no valves on the canister itself.
I had shared the diagram of the system in another post:


The system is rather simple - one line is vent, one is for fuel vapors coming from the tank and the third one goes all the way to the engine bay, where the purge valve(s) is(are) located.

If you have something else in addition to the three lines that go in/come out of the activated carbon canister, do you happen to have at part #?
 

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1999 S500; W140.051
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I have a '99 S500.

I have not had to replace the valve at the cannister. I have had to replace the one in the engine compartment (MOT) that it sounds like you have already replaced.

I did clean and lube the MOT valve before I replaced it and it did work for a while. There was never a problem with the solenoid clicking, but it appears that there was a problem with the sealing of the valve.

These valves are difficult to troubleshoot so I don't think it is worth the hassle of trying to limp the old part along with cleaning.

Evap system errors are a pain in general to troubleshoot and driving along with flashing fuel light is annoying.
 
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