:shakehead My vauxhall Zafira diesel had problem with its fuel injection pump. My mechanic changed with used one. Now the problem is with brain and coding. Took to vauxhall workshop they would not do coding and asked to get it changed with a new one by them for which they charge about half the current market value of the car. Any suggestion help and guidance will be appreciated.

It actually does need a new one. The new 'coding' takes into account that it is a new unit and wears out over time, which the coding accounts for.