Customer recovered vehicle, cut out while driving and wont start !

Global scan revealed no communication with engine and "U1100 CAN timeout with engine control" in most other modules.

Removed chip from key to check if immobiliser noticed it was missing and fault logged in that for transponder missing, assuming immobiliser working ok.

Obtained wiring diagram, checked all supplies, earths, relay operation and scoped CAN wires with unit connected, all appeared ok.

Suspecting fault with engine control unit, anybody else had similar issues with these please ?