Audi A3 V reg TDI won't start
 

I have an audi a3 on a V reg, 1.9tdi. When I put the key in to start it the coil light does not come on and turn off. The key light comes on the goes out. The car turns to try and start but won't. My Snapon solis says it can't talk to ecu. Do I have a wiring fault? The keys open and close the door locks as it should. I have had the car started since the fault but keeps stopping me from starting the car.