Check engine light came on, so we brought the car to the mechanic. I am told code P0030 - front O2 sensor bank. Mechanic resets and says problem seems to be gone, but O2 sensor needs to be replaced if it comes back on. Leaving the mechanic's parking ... light comes back on. I decide to get a second opinion from the Volvo dealership who tells me that they were able to see Volvo's specific code and that we need to change front AND rear O2 sensors. The car has less than 45k miles on it - this seems low for O2 sensors to fail. Also, why would two sensors fail at the same time? No one is able to answer that one.
What to do? (a) nothing; (b) change the front sensor bank and see what happens; (c) change both; (d) get third opinion in the hope of knowing what may be causing all these assumed failures?

Any help would be appreciated...

 

The oxygen sensors can go bad at random intervals though <45K miles seems early. I do know that the front sensor is prone to fail [more] than the rear. If the front sensor is bad then you want to get it replaced sooner rather than later. But to answer your question, I would start with the front and call it good.

 

Thanks 01_Fast_Ride - I will do that and posts the results.

 

Or if you can replace both and save the headaches for another thing later.
They are both prone to go bad.

 

Replaced the front sensor and everything seems fine ... so far. I guess I'll know what to do the next time the Check Engine Light come on.

Thanks for the feedback...

 

Glad all is fine.