like said the immobiliser will be linked to fuel pump and ecu will sense no fuel when problem occurs

so will throw dash light on as it senses fuel problem

so when codes read will read fuel related problem

so as garage have just read the code there are half correct

and obviously when cleared the code ecu returns to normal so will start

so imho its the immobiliser cutting in and shutting off fuel pump if its aftermarket immobiliser then it could be removed easy enough

but if factory fit could be wired to ecu which makes it harder to remove

hope this helps