Air-Fuel Sensor

[vl02720]

I recently had 'Check Engine Light' problem with my RAV4 and got the EGR modulator and VSV valve fixed from the dealer. Again I am getting the light and it seems it is code P1130 which is Air Fuel metering control ( is it same as A/F sensor ? ).
How critical is it to be replaced right away ? What problems could it cause if I wait?
I bought the 2000 RAV4 as certified pre-owned vehicle with extended warranty. Is this sensor covered under warranty ?

Thanks in advance for any useful pointers/replies.