How important is an oxygen sensor on a car?

Question

Going in for something else supposibly our oxygen sensor is seesed up even though its only 4 years ago it was replaced because of a recall.

Answer 1

O2 sensors are predominantly emissions control devices.  The main reason they are there are to insure compliance with emission laws and to protect the environment.  They can also help improve fuel efficiency by 15-25% which means a faulty sensor could cause problems for you at the pump.  The only component that can be damaged from a faulty o2 sensor is your catalytic converter (which isn't cheap) but that takes some time if it ever happens.  

On a side note, if it was recalled there may be something else to consider on several models of Toyota vehicles o2 sensors were burning out prematurely due to a fault ecm program if just the o2 sensor was replaced and the ecm was reflashed by the dealership the life of the o2 sensor was severely shortened as was the catalytic converter (Toyota wasn't the only manufacturer with this problem though).  As a result Toyota extended to warranty to 80000 miles on their 02 snsrs.  You may want to check your dealer for any TSB's related to this problem.

  Some additives and engine flushes can also burn out 02 sensors.  Hope this helps some.

Answer 2

The O2 sensor is the fuel management device that either causes the pulse width of the injector to increase or decrease. If it fails or goes lazy, it will set a code that the driver will see as a check engine light. A poor or non functioning O2 sensor will greatly effect the performance of your vehicle, in performance and gas mileage. If you have doubts about its functional ability, it can be observed with a scanner. The faster it switches from a high and a low voltage setting the more active it is. Mid range is .45 volts. Don't replace it unless it is proven to be bad. These things are not cheep.

Answer 3

Might as well.

the 02 sensor monitors exhaust gas coming out of the engine and sends the signal to the computer to for ai/fuel adjustments.