hi, need some help diagnosing if i have a faulty o2 sensor. any garage i spoke to just want to through sensors at it till its fixed, they arnt paying for it though. symptoms are, alot of black smoke when accelerating, mpg dropped 10, no fault codes, regenerating the dpf alot, hesitant, misfire when idle. lambda ratio minus 0.5 to o.8, lambda voltage bottoms out at 0.01 volts on my obdll reader, maf sensor reads from 10g/s to 170 g/s. anyone else seen symptoms like this so i can change the actually faulty sensor and not guess work. pic attached showing lambda voltage dipping. thanks people😀