I had a check engine light, so i plugged in my OBD2 reader and it said "02 Sensor Circuit no activity bank 2 sensor 1". It also notified me that I had 2 misfires in cylinders 4,8. So thinking that the O2 sensor was the main culprit, I ordered some Bosch 02 Sensors. Couple days later I install the new sensor and everything seemed fine, until 10 min later the service light illuminated. So I plugged in my obd2 reader and it said "02 sensor circuit Bank 1 Sensor 1" P1030. I was wondering if you had to replace the o2 sensors in pairs? (I ordered another one already)

 

Its ideal to replace them both but not necessary.

 

Bosch O2 sensors have also been reported to have a high failure rate out of the box.

 

 

Or reinstall the original 1/1 sensor.

 

I went thru 3 pair of Bosch sensors before I gave up and went with Walker from A British.

 

I am happy to inform you guys that the new sensor has fixed the problem! There is no more service light. However I found the problem was that the sensor was filled with oil. My disco sadly has an oil leak (2003 Land Rover Disco 2 HSE with 104,000 miles)

 

You likely have a plugged valve cover baffle, remove and replace with Pcv mod and your oil leak will go away