Went to change the standard ecu on my octy mk1 after getting one that's been remapped but it would not run the car the light with car and key symbol was flashing so changed it back to the standard one now I have the engine management light on any advice would be greatly appreciated thanks in advance Si.

You can't just swap an ECU, it needs to be programmed to the car (unless it has been unlocked).

Haha ok will take it to a centre to have it checked and see if they can unlock it for me is there anyone that has the computer and lead to connect to my car and clear any fault codes that have caused the engine management light to come on thanks tech 1 e for your help