does it really need to be replaced

 

Philosophically or is this a trick question....

 

seriously. the mechanic was not certain

 

Any more info on your MINI since you posted this question in the wrong area of our forum ?

Did your mechanic mention a code ?

 

no he just said the reason for the engine light coming on was the c02 sensor

 

CO2 or O2? Because I have never heard of a CO2 sensor.

 

if its the O2 sensor the owners manual on my 07 MCS said to replace them every 120,000 miles.

 

Depending on your build, there is an extended warranty for some 02 sensors....you really need to post up more info to get the help you seek.

 

And WHICH o2 sensor....
The post cat...which monitors the cat and its efficiency or the upstream o2, which the motor uses to monitor the fuel/air mixture.....

 

Unless you have contaminated your sensor with leaded gas or silicon, the 120,000 mile interval should be the only normal reason to replace your sensor. That being said, one does ocaissionally fail usually from thermal shock (water splash on the sensor after the heater starts) or a sealing failure at the wire exit side.