Two issues CEL with code P0030 & rear wheel bearing grind

Hi everyone, first time post here so hopefully I've put this in the right area
Over the last couple of weeks I've had a slight grinding in the left rear wheel when turning left, mechanic suggests wheel bearing. Would that be correct as it's only when the wheel is unloaded?
Also am I better off getting an oem part or not?
On a separate note, just yesterday I started the car and the cruise control started flashing. After the drive I got back in the car and started it to go home, this time the CEL was on as well as flashing cruise control
. I got the code to display on the dash and came up as P0030. Car seems to run completely normal with the occasional sulphur smell if I do a bit of sprinted driving.
Any idea what would cause that code? Bad O2 sensor?
I did search a bit but thought I might get a better answer asking here.

Over the last couple of weeks I've had a slight grinding in the left rear wheel when turning left, mechanic suggests wheel bearing. Would that be correct as it's only when the wheel is unloaded?
Also am I better off getting an oem part or not?
On a separate note, just yesterday I started the car and the cruise control started flashing. After the drive I got back in the car and started it to go home, this time the CEL was on as well as flashing cruise control

Any idea what would cause that code? Bad O2 sensor?
I did search a bit but thought I might get a better answer asking here.