2004 Honda Civic O2 sensor?

My CEL has ben on and I took it to two different mechanics who gave me no information so I bought my own code reader. There were two codes that came up: P0135 and P0134. I know that means it's a problem with my O2 sensor but what is wrong exactly? And does it need to be replaced?

With both those codes, being both O2 codes one for a short either in the wiring harness or inside the O2 sensor and the other code for no response same O2 sensor upstream from the cat. Chances are its the O2 sensor. Bench test the O2 sensor this video is multi wire test but you can research yours good luck

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