I had Oxygen Sensor Engine Light that complained about the Bank 1 Sensor 1. I used my OBD2 tool to clear the code, and the engine light is not coming back.

Can I leave the sensor as is or still I should replace it since I had the OBD engine code at least once?

Update after a week

The engine light came back. Lesson learned: Once you see the code, the sensor needs to be changed.

Final update

I replaced the sensor and the engine light is gone for good.

  • How long has it been since you cleared the code? Do you know that the system is reporting in a ready status?
    – dwizum
    Jun 20, 2019 at 14:26
  • @dwizum, I cleared the code 24 hours ago, but I did not do any intensive driving. How many miles should I drive untill I know the initial code was a false alert?
    – Allan Xu
    Jun 20, 2019 at 15:02
  • @Allan Xu Depending on your car manufacturer's smog tests and your driving patterns I've seen oxygen sensor tests clear up in 2-3 days of normal driving. Jun 21, 2019 at 15:09
  • I've also seen CELs come back after 2-3 days of normal driving. :)
    – Huesmann
    Jun 21, 2019 at 15:19

2 Answers 2


If a code came up and you cleared it without fixing it, it will come back. Once you clear a code, the computer resets the Readiness monitors and start to conduct a new drive cycle test routine. Since you didn't fix the problem, it will probably fail the drive cycle and light the light again with the same code. Read this post on drive cycles and readiness monitors


It could also be a one time anomaly. If it were me I would wait to see if it comes back a second time since you already cleared the code. If not, I wouldn't worry about it. If it comes back, time to fix it.

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