Engine Running Lean

I have a 2005 Toyota Carolla, and my check engine light recently came on. I had someone test the code, and was told that my engine was running lean. I’ve been told in the past with a previous car that when the check engine light comes on as a result of the O2 sensor, that it is very expensive to fix, and not particularly worth the money as far as the life of the car is concerned. Is this true? Could I be doing any damage by ingoring this signal

We need the actual code. Some “too lean” codes like P0174 can be cured with a Mass Airflow Sensor cleaning. Not overly difficult if you follow the directions on the can. Suprisingly some “too lean” codes respond to fuel and air filter changes, I know sounds a little odd.

I agree with oldschool. We need the actual code to be able to help you. It might just mean that you have a vaccum leak somewhere.