Q's about oxygen sensor

[wcelica87]

What is the symptom of a bad o2 sensor? and what is average life of o2 sensor? and finally can a bad o2 sensor make your car perform poorly and give you bad gas mileage? thanks.

[BoonyBoun]

A bad o2 sensor can activate the check engine light, and can also cause lagging.

[celwin]

Originally posted by wcelica87
What is the symptom of a bad o2 sensor? and what is average life of o2 sensor? and finally can a bad o2 sensor make your car perform poorly and give you bad gas mileage? thanks.

Yep, lag and bad gas mileage are symptoms of a bad o2 sensor. Mine went bad recently. I have 32,000 miles on the car. If you suspect yours is bad take it into the dealer. A bad o2 sensor could make your Cat fail prematurely.

[ToyRolla]

02 sensors are tricky to diagnose. There may be a broken vacuum line, clogged air passage, etc...

If you were able too hook up a meter to the 02 sensors you'd find that the first one should go up and down (but not sharply)and the second should flatline.

If the second 02 sensor reads like the first one (if the first one reads normal), you most likely have a bad catalytic converter.

If the readings on the first one are at too high or low frequency or the readings are irratic. It will affect your gas mileage. For Example, If the 02 sensor reads a lean mixture, it will add more fuel to the mixture. (you lose gas mileage).

If the 1st 02 sensor flatlines, usually just the 02 sensor is bad.

Lastly, you can check readings with a voltmeter at a connector, and it must be when the car reaches normal operating temperature.

[ToyRolla]

Also.. make sure you run the correct octane in the car. Some cars are sensitive to octane differences.

[wcelica87]

does a bad o2 sensor trigger a check engine light?

[iwantaferrari]

dude, the second person that posted in this thread just said yes it can trigger a check engine light, and yes in an OBDII car yeah, the O2 sensor being bad, the cat being bad will trigger the check engine light