I have a 2008 Roomster 1.4 16v, the EML came on recently, the emissions have been checked and are perfect, the code reader shows "EVAP purge valve open circuit", a multi meter across the 2 pins in the valve body shows a resistance of 24 ohms, does this mean that the valve is open and the wiring in the valve has this resistance?

 

That sounds like a reasonable resistance for the solenoid coil of a valve like this. I've just put my feet up, or I'd pop out and do a comparative measurement for you on one of our cars with (I imagine) similar valves. 'Open circuit' means disconnected, or coil wire broken, so I would be examining the wires at/near the loom connector for signs of damage. From your resistance measurement, I'd think the valve itself is not the problem.  

 

As it turned out, I had to get up, so I checked the valve on my Polo for you. Part number is 6q0906517, and it measured 27 Ohms on a very cheap-and-cheerful multimeter.

So that confirms my belief that your valve is OK.

Thanks for your prompt answer & taking the time to check, I will check the wires etc as you suggest.

No problem. Your valve does appear to be the same, as shown here.

 

Hope you find an obvious, and easy-to-repair wire fault.