I have two OBDII codes P1139 and P1258 what does these mean? on 1996 Cadillac Seville SLS

I have two OBDII codes P1139 and P1258 what does these mean?

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DTC p1139 - Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 2

DTC p1258 - engine coolant temperature is more than 131°C (268°F). When the engine is overheated, DTC P1258 will set. The PCM will disable two groups of four cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders, the PCM is able to reduce the temperature of the coolant.

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