How do I remove the dang Engine Temp Sensor?

[Stormtruck2]

2004 Ballabio. The plastic around the temp sensor has broken off, and there is nothing for the socket to grip.  At this point it looks like I may have to remove the head in order to remove it.  The only thing to get a hold of is a round metal thing sticking up in the hole. I'm open to suggestions here. 

[JBBenson]

I had the same problem, ended up using this, came right out.....remember to soak in PB Blaster first:

[vuzzi]

I did it with a punch, gently punching it at one of the corners of the bolt

 

 

 

[MartyNZ]

...and a third way is to use a screw extractor. It winds into the hole in the metal remains of the sensor housing, and you can unscrew it easily.

I fitted a brass temp sensor housing instead of the plastic one. MG part no. 30163301.