2003 Toyota Camry Rear O2 Sensor Affect Smog Test?

I have a 2003 Toyota Camry. I want to know how does the rear O2 sensor affect my car other than not being able to pass smog test.

I got the P0420 code for my 2003 Toyota Camry 4 cylinders. I was told it was the rear O2 sensor that is bad. I know the front one tells the computer how much fuel to dump in and the rear O2 reads the reading from the emissions.

My question is, does the rear O2 affect gas mileage and does it affect the car negatively in any way? If I don't replace it will the car still be fine? Other than not able to pass smog only, it won't affect it at all, correct? Can it damage the catalytic converter if left unfixed? If changing the rear O2 is just for passing smog only, then I don't plan on changing it until the time comes. But if it causes any damage to anything then I will change it asap. Thanks.


Answer:		The rear oxygen sensor on your Toyota Camry does not affect engine performance nor gas mileage. It is simply in place to determine the catalytic converter's efficiency. With that said, if it is defective, or throwing a CAT efficiency trouble code because the catalytic converter is defective, your Toyota Camry will fail the smog test; but only if there is a trouble code present. You've mentioned P0420 exists. If this is the case, you Camry will not pass the smog check. The Check Engine Light being illuminated, or a trouble code stored in the ECU (engine control unit) will automatically cause your vehicle to fail the smog check. posted by SmogTips Support

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