I have also heard from the company who supplied the sensor (Carparts4less), regarding the warranty. They want me to fill out a warranty form with all the details of the fault and send it back to them along with a copy of the original invoice and also the component itself. The claim will take 4-6 weeks as they need to send the component back to the manufacturer (Bosch) for testing.
Now, I have two problems with this:
Firstly I must have thrown the invoice out with the box. (Really annoyed with myself about this as I keep bills and invoices for everything!).
Secondly and more importantly I can't be without my car for 4-6 weeks while they sort it out! I was hoping they would send me a new one and then I could send them the old one.
Will give them a ring tomorrow and explain the situation, but if anyone has any suggestions as to what I can do, then I'd love to hear them, as I feel a bit stuck now.
Also keep coming with the suggestions as to why the fault may have reoccured in the first place.

Cheers guys,
Nick