elc went off after battery change

[Yuta]

The ecl has been on for a while. The code indicates oxygen sensor aging problem. Today my battery completely gave up and I put on a new one. And then after a while of fluctuating idling, the ecl went off ...

Who can tell me what happened? I already ordered the sensor.....

[mikefocke]

You changed the battery and, because of the time the battery wasn't powering the car, the computer causes a reset and the whole adaptation process begins again. So replace the aging sensor and try again and expect that, while the computer relearns, the idle will be rough and it will take several starts and types of running before the ECU learns how to manipulate the signals the sensors are sending it.

[bell]

Mike is correct, although if you scan the car the code should still be stored, since it is not” current” then the cel won't come on....

[mikefocke]

The CEL is only an indication that the computer interprets the signals as defining a serious problem. There are codes that exist below the level of serious where the CEL doesn't come on but which still give you a diagnosis of a problem that should be fixed. And the causes of those codes can give you drive-ability problems.

Not knowing where you are located nor what the pollution vehicle checks are there or how important they are to you, we can only warn you that the O2 sensor will not immediately cure everything because the computer has to learn what is normal from the new sensor.