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2003 Toyota Highlander Question: OBD II shows front upstream O2 Sensor is bad.

 

Question

cheifpod1, 3.0L V6, Milton, FL, July 04, 2012, 09:33
 Rookie

Parts available give me two choices. O2 sensor and Air Fuel Ratio sensor. Which is it? Location is Front manifold pre cat.

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  • Answer #1

    July 04, 2012, 10:05
     Master

    was it 'Toyota' or aftermarket 'parts' that asked you that question?I'd bet it was advance or autozone. It's an a/f sensor pre-cat , O2s , after (or in middle) of cat (downstream). one is for engine management the other is for emissions monitoring.(short explanation). Safer and less costly to keep your Toyota , all Toyota!!

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    cheifpod1, July 04, 2012, 11:58
     Rookie

    Okay so you are saying manifold location pre-cat its called an a/f sensor and post cat its called an o2 sensor right?

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    ziptie12, July 04, 2012, 13:30
     Master

    Yes and I'm also stressing the importance of an OEM part. (I understand the $ difference for what should be the same part , but they're not). As I said in my first response they perform different functions.

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