Non Start - Cranks normally but will not start--NB (MK2)

No spark at the plugs & no fuel being injected. DTC 51 may be stored.

A common component to fail and give these symptoms is the crank sensor. It is located on the front of the engine, the 3 wire plug can bee seen on the left side mounted on the timing belt cover behind the power assisted steering pump drive belt.

This is a hall effect type sensor so can be tested by checking for 12v on the white/red wire, ground on the black/yellow wire and a switching 0v - 5v while cranking on the grey/blue wire (this is best tested with an ociloscope).