O2 sensor question - second sensor....

[99gst_racer]

Take a look at the first pic. It is a pic of my floorboard with everything ripped out. I found this plug (circled) unplugged. The second pic is an upclose pic of it plugged in. This is my second O2 sensor, right?? If it is, that means it has been unplugged for the past 2 years, ever since I installed my seats. Here comes my questions:

* What exactly does the second O2 sensor do?
* How could it negativily effect my car w/ it being unplugged?

Any help would be greatly appreciated.

Thanks -Paul-

 

[Spln_Hrd]

the sensor is there to take referance from your front o2 sensor and then make sure the oxygen levels are differant. in other words it makes sure you have a catalytic converter.

the damage that can be cause by this. hmm a burnt check engine light bulb. :laugh:

 

[99gst_racer]

I do understand what an O2 sensor does, but I guess my question is: Why is there two O2 sensors? And What do they do differently? Is it hurting my cars performance/drivability by having the second one non-functioning?

Thanks.

 

[Catbox_95]

It's more than just a cel that you will have. I don't remember which, but having it disconnected will cause your car to either run too lean or too rich, or maybe a combination of either one at different times. It is important to have a good working second O2 sensor. (or an O2 sensor-delete like I have)

 

[CanadianTSi]

I havne't had my 2nd o2 sensor for 2 years now, and my car runs fine.

You get used to the light after awhile

 

[Syndicate13]

It's more than just a cel that you will have. I don't remember which, but having it disconnected will cause your car to either run too lean or too rich, or maybe a combination of either one at different times. It is important to have a good working second O2 sensor. (or an O2 sensor-delete like I have)

This post is completely false. On some cars not having signals from both O2 sensors will make the car go into limp mode but not on DSM's. The only negative effect you will have without that rear O2 sensor is a CEL. It seems almost a toss up as to who gets it though. Some ECU's are more sensitive than others, mine would only go a few miles before tripping the CEL. My friend's GST never had a CEL in the 8 months he had exhaust before he sold the car.

 

[psychlow]

The rear O2 sensor affects performance on very, very few vehicles.

As stated earlier, the reason it's there is to measure a difference in lambda (measured O2) between the front O2 sensor and the rear. In looking for a higher O2 reading than the front sensor, the system is designed to make sure that there is oxygen being stripped off of the oxides of nitrogen (NOx) generated from combustion. This is the function of the catalytic converter. The nitrogen naturally wants to combine with other nitrogen molecules to form stable N2, and the oxygen does the same with other stripped oxygen molecules to form stable O2.

NOx plays a large part in photochemical pollution, and thus, the idea is to end up with nitrogen, a gas that our atmosphere is nearly 80% of, and oxygen, which we breathe everyday.

 

[Spln_Hrd]

I havne't had my 2nd o2 sensor for 2 years now, and my car runs fine.

You get used to the light after awhile

yeah i got so used to mine i missed it after i shut it off w/ my datalogger

 

[Syndicate13]

yeah i got so used to mine i missed it after i shut it off w/ my datalogger

I would feel weird driving the car with it off if I ever had to unhook the battery. Took me a while to get used to it not being there after I put in DSMlink.