O2 Sensors – When Should I Replace the Oxygen Sensor On My Car?

Reader Question hi austin,
i love your strait forward good advice articals.
can you give me some info about oxygen sensors.
i see that they run around $30 to replace & are suspose to give you better gas miliage, is this true & is it worth the $30 ? What are some of the car symtoms that would tellme that i need to relace the oxygen sensor besides waiting for the engine light to come on? Any info you could give me i’d be greatful.

thanks a bunch

Hello there Ron,

Thanks for your kind words. An O2 sensor controls fuel mixture, so a weak/lazy/bad sensor will usually cause the fuel mixture to be much to lean or rich, both of which will make a funny exhaust smell, probably cause exhaust smoke, poor fuel mileage, lack of performance, hard starts, failing an emissions test, and setting the check engine light.

If you don’t have any of those symptoms, I think you will just be wasting your time and money replacing it. Although I do know a few shops that love to replace them at 60,000 miles as “routine maintenance”


Austin C. Davis

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