Downstream oxygen sensor has 0.0 voltage? Catalyst's Oxygen StorageCapacity 0?

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Toyota Corolla 2010 shows "No Powertrain DTCs or Freeze Frame Data is presently stored in vehicle's computer" , with oxygen sensor and catalytic sensor not ready, other 6 ready; since replacing Speedometer Sensor 1 year ago. 800 Miles driven, following Toyota Driving Patterns 3, 4, 9, 10 for all types of oxygen sensor and catalytic sensor. No luck. 1.8L 4-cyclinder engine. Only 23000 miles. No lights, No OBD2 codes. Scanner shows: downstream oxygen sensor voltage: max 0.000, min 0, test 0, status OK upstream oxygen sensor voltage: max 19.8, min 0.119, test 0.702 status OK Catalyst Efficiency - Oxygen Storage Capacity of Bank 1 max 0.000, min 0, test 0, status OK I wonder how can the downstream oxygen sensor has 0 voltage. It should be stable 0.5-0.7,right? Is the Oxygen Storage Capacity tested 0.000 OK? Does ""No Powertrain DTCs or Freeze Frame Data is presently stored in vehicle's computer" matter ? Could the Speedometer Sensor Replacement job hurt these sensors ? Thanks a lot.