Hello, I have a saxo vtr with engine management light on.... I used a code reader to see what's wrong and it came up with these codes, P0420, P0135, P0130. What are these and what could I do to solve the issue? If it helps I have an induction kit and cat back exhaust if it makes any difference? I have recently changed manifold too, it had a crack in it so replaced it with second hand manifold but still standard style one. It hasn't got a new gasket on it and currently missing a stud on the manifold but would that cause the management light? Also it backfires at redline.
Thank you for your time
Dan
Thank you for your time
Dan
