Citroen C8 Engine & Drivetrain Problems

Car made a small 'beep' . Message displayed stating purification filter . Engine/gearbox warning light lit up & car now in limp mode.

Hello all, I have a Citroen C8 I have just replaced the whole engine due to previous injector non removal issues, however upon rebuild I now need some ancillaries, one being the steel water pipe that is positioned at the rear of the engine,...