I have a slow o2 sensor?

Question

I have a 99 Toyota Camry LE, that has been getting 11 mpg city. When I took it to a reputible shop I was told that my first o2 sensor was slow. It will cost a minimum of $230 to swap it out, however he is not sure it would be worth it.
Also everything else has been checked. Any advice?

Answer 1

O2 sensors need to switch between 0 + 1 volt very quickly within a very small period of time however O2 sensors are also affected by information from other sources ie mass air flow sensor and even rear O2 sensor
A dirty air filter can and will affect airflow and will affect at what speed the O2 sensor reacts and at what voltage, best to get someone with a reasonable amount of knowledge to check your car properly.
Where I live O2 sensors are quite reasonable in cost and it would seem your quote includes a fair amount of labour, get a second opinion and also remember that if someone diagnoses a sensor and it doesn't improve or sort out original complaint, TAKE IT STRAIGHT BACK to them!!
Hope this helps.

Answer 2

An O2 sensor just draws a current proportional to the amount of oxygen in the exhaust. They do go bad, but $230 is too high. A genuine OEM sensor is about $80, and a generic is only $40 or so. They take 10 minutes to replace.