I just purchased a 2011 Volvo XC90 with 102k miles. I use 93 octane gas. On the drive home from the dealership, the check engine light came on. The ODB-II codes are P0420 and P0430:

P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Catalyst System Efficiency Below Threshold (Bank 2)

Any thoughts on the most common cause of this in a 2011 XC90? Is it an O2 sensor fault? Mass Air Flow (MAF) sensor? Air intake leak? Or the catalytic converter (seems unlikely)?

 

What engine does your car have? The P0420 code is saying there's too much of a differential between the front o2 sensor and the rear o2 sensor. This can be caused by an exhaust leak (particularly around the flex pipe) , an o2 sensor issue (typically the rear as the front controls the fuel mixture - which when off will throw other codes) or possibly an intake air leak or throttle body issues (less common). Anything else going on - ie driving in snow or rain etc? Did you try clearing the code to see if it returns (it may take 50 or so miles to reestablish).

 

Thanks for the reply. Engine details:

2011 Volvo XC90 AWD, 6-speed automatic transmission
Engine code: 3.2 6-cyl B6324S
Engine size: 3,192 cc inline-6 (straight-6)
Engine type: gasoline, DOHC, naturally aspirated
Oil: 5W-30, 7.18 US qts (6.8 L)

I live in Pennsylvnia --there is some snow on the ground but the roads care clear.
I cleared the code using a Foxwell NT201 OBD2 scanner; the light went on again 8 miles later, this time with just the P0430 error.

The P0430 is what first lit up on the drive home from the dealership. I anticipate that the P0420 will light up soon as well --with a bit more driving.