Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
The PCM detects that the affected HO2S 1 voltage is between 250-650 mV for more than 16 seconds, during a 20 second monitoring period.
If you have replaced this sensor with a known good one, then there is a chance of wire damage to that sensor. As well, some aftermarket sensor could set false codes as well.