Again with the 02 sensor, when will it end?

[pathman87]

So i'm sure everyone agrees this 02 sensor stuff is bull. mine just went last week too, i can't find a new one anywhere in my area... how important is it to get fixed? it's just a sensor on the exhaust right?

[nissandoms47]

that 02 sensor senses the oxygen levels in your exhaust. From that it adjusts your air fuel mixture to the best mixture. With a bad 02 sensor your gas mileage will decrease and it pretty much just sucks.

[Buzzman]

I went back to the dealer with mine. I thought maybe I should have gone to an independent, or possibly buy and change them on my own, but after reading some of the other threads, I think I did the right thing. I haven't had any problems since.By the way, there are 4 sensors in total. The ones that seem to fail are the 2 rear sensors. I haven't had to replace the upper sensors yet. FYI, mine is an 2002, with 160 Kms on it (Ottawa, Canada).Hope this helps.

[mungerla]

I hear you had to replace both rear sensors. I need to do the same thing and I need a diagram or something to find these. What did you use to locate the sensors?

[todapark]

Ah the old O2 sensor issue. If only it were as simple as having a code reader designate a particular sensor problem. The O2 sensors basically are a feedback component in a closed loop system. They relay the exhaust gases composition to the computer and then it adjusts the fuel to air mixture delivered to the engine via the injector duty cycle. Sounds wonderful and it is when all things are perfect. But sometimes in the real world all is not as it seems. Yes if you are not getting any feedback from an O2 sensor, it is probably bad however if you are getting a high reading from the sensor , well it may just be doing it's job and reporting just what it is detecting. Unfortunately in todays world of low octane fuel and even lower octane ethanol, you may get an error code from a sensor simply because the computer has been programmed to deliver a certain fuel to air ratio because of the feedback it is receiving from the O2 sensors and other sensors, however the computers programing is based on a certain octane level in the fuel. So what happens when an O2 sensor does actually go bad, of course the little pain in the arse check engine light comes on, but at the combustion level usually your fuel consumption increases, that is gas mileage goes down and your engine runs richer, somtimes you will actually feel a bit more power from your overly rich running engine. Now to trouble shooting, I have a homemade cheater cable that fits the O2 sensor connectors and simply swap the connectors from one side to the other and then reset the codes and drive the vehicle until the service light comes on again and then check the codes to see which sensor it says is giving a bad reading, if the code reader shows a different sensor than before (because I swapped the connectors) then I know the originally designated sensor is bad however if the code reader shows the original sensor to still be bad even after swapping the connectors then I know that the sensor is simply showing what it is seeing and it is the fuel to air mixture that is the real culprit. Hope this helps and is not too confusing. PS I drive a multitude of different vehicles and on 8 out of 10 of them the check engine light is on, it seems the engineers tried something good but turned it into a money making ide because every little old lady who sees that light will take their vehicle and their money to a dealer for service and it is their wallet that will be serviced to the tune of a few hundred dollars and in a week or so, that little service engine soon light will be on again.

[slickroger]

Hi All,

I just changed my O2 sensor not to long ago, and i have noticed a difference in gas mileage.

I swear i seem to have gotten like 50-75kms more per tank since i replaced the sensor.

My engine light came on and the code reader gave me these 2 codesP0138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)

I bought a new sensor after letting the light come back on a couple more times so i knew it was that sensor and that sensor alone that was the problem.

replacing the sensor was pretty easy just in a real tight spot considering the wire for the sensor runs a long the back of the engine.

Heres the location from underneath the truck

Heres the connector under the hood

Good Luckhope this helps because thats y i made it.


Modified by slickroger at 1:17 PM 7/1/2008