got a e53 petrol 3.0 that has engine check light on and erratic engine idle.

(Peake code reader gave faults as Table 19: CA -O2 sensor control limit cyl 1 -3 and C6 catalytic converter efficiency cyl 1 - 3 plus some misfire ones).

My question; Is this indicating an air leak after the maf or something related to the O2 sensors?

ideas appreciated