XC60 2019 diesel ,Please help i'm going round the bend.I changed the lambda sensor in the engine compartment which kniocked the code of for 2 months then it came back then i took all the lambda sensors out and cleaned them the code went away for 1 week.Ive put cataclean in the fuel but the codes back ...What next please....Any advice greatly recieved.The MPG is now down to 32mpg :-(