2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
On the code if a shop or if you are doing the repairs. There's two O2 sensors and it's possible, depending on sequence of repairs that the harness / O2 sensor may have been damaged or it's a poor quality aftermarket O2 sensors. A O2 sensor extender may resolve the problem, the type of catalytic converter may also be the cause. How many miles and what type of driving, highway or city, since installing?