Roverlike

Your SRS error is related to left hand side pretensioner. First thing I would look is weather or not SRS light is iluminated or not in order to see if this is historical error, or present one. If present one I would start with connector to the pretensioner under your seat. Be warned that you should disconnect your battery when working on anything related to SRS to prevent accidental deployment of airbag.
This error is related to high resistance in the circuit from SRS ECU to the left hand side pretensioner. High resistance is usualy problem of bad contact in the connecotr, but it can be related to pretensioner itself or bar wiring to the pretensioner.

However this eror has nothing to do with your engine starting and running only 3 seconds.

Your alarm is disarmed is it?

Regarding your engine fault, this also could be problem of management multirelay (consist of four relays together among which one is responsible for fuel pump).