O2 Sensors bad, Check Engine light on

[hiimatif]

My 2015 M4's well out of warranty and one of the O2 sensors have gone bad (check engine light on). Planning to replace both because I've read here that once one's resolved, the other one could go bad right after.

I'm seeing the Oxygen sensors will be about $300 each just for the parts. I also came across ones by Walker that are closer to $100 each. Does anyone know if they might be legit and if I can get them instead?

[behindthen0thing]

there are 4 o2 sensors.

the precat o2 sensors have to come from BMW so it's been told.
The 2 post cat sensors can be aftermarket like bosche or whatever.
They are easy enough to change. Get the car in the air, remove the aluminum pan and you'll see what you need to do. you'll need some offset angle wrenches as well.

[tom @ eas]

Stick with OEM when it comes to something as vital as O2s.

[dcpatters]

Are the fronts wide-band sensors?

[behindthen0thing]

Originally Posted by tom @ eas

Stick with OEM when it comes to something as vital as O2s.

The post cat sensors don't control anything and most often it's the heating circuit that goes out. There's no harm in using a quality bosch sensor.

[tom @ eas]

Originally Posted by behindthen0thing

The post cat sensors don't control anything and most often it's the heating circuit that goes out. There's no harm in using a quality bosch sensor.

Post O2s are responsible for long-term fuel trims.

Bosch is OEM. Just stay away from the off-brands.