I have a 2000 Camry le V6. It was given to me by a family member who never drove it to much and was parked under a shed when not on the road. It has only 52,000 miles on it and looks new. The check engine light came on the first time I drove it. Engine showed no signs of any problems. Took it to Auto Zone and had the code pulled that showed a bad oxygen sender. The top one that is easy to get to. I replaced it. Light went out for about 20 miles then came back on. I have tried to reset the light by undoing the battery cable for a hour. Done this 3 times so for but the light still comes back on. Also I have looked at the gas cap and it looks fine. I make sure it clicks when putting it back on. I checked the gas mileage on last fill up and it was 24 mpg. Mostly stop and go driving in town. Any suggestions on what makes my check engine light to keep coming back on? Thanks

 

There is more then one top sensor.

What was the exact code?

 

I believe the code was P420 or P0420

 

P0420 is Catalyst System Efficiency Below Threshold (Bank 1). Bank 1 is the cylinder head nearest the firewall.

See links below:

https://www.obd-codes.com/p0420

https://www.openbay.com/blog/why-o2-...gnostic-tests/

If a bad sender typically there would be codes indicating this and which one it was.

Might recheck with AutoZone on code(s).

 

Thanks, I will get the codes read again.