Hi Oldford, thanks for your reply.
The AA came up with 2 fault codes originally - P1631 (main relay power hold) and P2338 (cylinder 3 knock)
I had a diagnostic done by a secondary garage before i went back to the originally garage, and this provided also P1631 and P2338, however also suggested P0100 (mass air flow sensor) P0203 (injector circuit malfuntion cylinder 3) P0204 (injector circuit malfunction cylinder 4) and P0202 (injector circuit malfunction cylinder 2) !!

However when i returned to the original garage who supplied the injectors, they told me it was reading the fault codes because the seals were broken and therefore the sensors were not reading correctly