54reg zafira petrol?

it means the computer thinks there is too much air going in, as measured by the flow sensor.

Surprised you missed all these when you did that Google search of your own, for Zafira P0103 fault code, but what the hey. Here's what i found in the first few results:

https://www.obd-codes.com/p0103

https://www.vectra-c.com/forum/showthread.php?197898-P0103-fault-code-HELP!

https://repairpal.com/obd-ii-code-p0103

http://www.troublecodes.net/pcodes/p0103/

https://www.youtube.com/watch?v=ExzZgfsPnYs

HTH
July 2017