Have a 2004 1.5 DCi was travelling along at around 70mph then had 'Injection Fault' come up on the display and the STOP light pulled over engine still running message disappeared along with 'STOP' light, pulled away again fault and light came one almost straight away, pulled in and car stopped running and would not restart.
AA man did some checks and said he was 99% certain it was the crank shaft sensor (plugged his computer into the machine and it was not showing any fault codes), got the car to a garage and mechanic agreed with the diagnosis (he also did not have any fault codes when plugging in the computer)and changed the sensor (and the battery that was well past its sell buy date!) collected the car which had been tested got 1 mile down the road and had exactly the same fault and car again would not restart

The car is now obviously back in the garage awaiting another look by the mechanic in the morning, but would be interested if you lot out there had any ideas.
Thanks