I get them from ebay. For info, the front one is for the fans. This can also cause EOBD errors on the dash. So replace both if they are showing Verdi Gris
http://www.ebay.co.uk/itm/12V-Mini-M...item3382841490 Buy a spare as well.
Use some dielectric or silicone grease on the connectors to keep the moisture out.