I have had a check engine on a 2001 Subaru Legacy for some time now. Went to mechanic to fix few other things and he told me the oxygen sensor and catalytic converter needs to be replaced. The catalytic converter was installed by the small dealership I got the car from around January this year. Assuming the emissions fault code is not due to the catalytic converter, can the O2 sensor trigger such a code?
UPDATE I bought a BAFX Bluetooth OBD2 Scan Tool and tried it today. Although the check-engine light went away after the serpantine belt was replaced, I checked with the tool and got Fault Code P0420. And the O2 sensor bank 1 sensor 2 (picture attached) was showing 0.1V-0.3V. I cleared the codes and will see if it comes back in few days. Could the bad belt/wheelie trigger this error?