About a month ago, I got a CEL to change the O2 sensors. I haven't noticed a performance or fuel efficiency drop. Should I change the proper sensors right away or can I let it go for a bit. Also, are their any issues with using a cheaper NGK sensor as opposed to the more expensive OEM part?

 

You can wait if the CEL lamp does not bother you, or if ou dont see a change in performance. Mind you the rear sensor does not feed into the ECM in a closed loop feedback for engine management. The rear sensor will never affect performance.

Get the least expensive O2:

buyoxygensensors.com

 

as a side note, did you pull the codes to determine the CEL lamp had to do with O2 sensors?

Personnally the cel lamp annoys me to the point I would have not waited a month.

 

Change it now...malfunctioning O2 can destroy your cat

 

Thanks for the advise. I'm going to replace them with Bosch sensors.