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Q: Hello, I had a 02 sensor downstream placed in my car so I had another diagnosis done and it's saying 02 sensor.. so should I have

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Hello I have a 2003 Buick century customs and my engine light came on I went to AutoZone and had a diagnostic done it read Error code P0135 H02-11 Bank 1 sensor 1 Heater circuit malfunction.. I had replaced the sensor 02 downstream but light still on a it's reading the same thing should I replace the upstream sensor also? Thank you

My car has 174000 miles.
My car has an automatic transmission.

Sensor 1 would be the upstream sensor and Sensor 2 would be the downstream sensor. Replace the upstream sensor and you should be fine. NOTE: I have seen many vehicles throw a Sensor 2 fault soon after replacing Sensor 1, so you beat yourself to the punch !!

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