Unusual noise.

Hi all,
So I was driving to work when I heard a loud bang and then the sound of something hitting the underside of the car, I looked in the rear view mirror to see if anything was there but nothing, was a funny type of bang, didn't seem like a backfire more like something snapping or shearing off, The dash the lit up with the engine light, cruise and SI-Drive were flashing and the traction control indicator was also on, I then had to stop at traffic lights and the car stalled on me, I had to turn the ignition off and then the car started again still with all the lights, I do have a basic OBD scanner which came up with error code P0340 which is the Crank position sensor, I've now cleared the code and the car seems to be running just fine, Any ideas out there, the car is a 2010 Impreza WRX STi Hatchback.