On Sunday my SES light came on. I needed to exchange a set of light bulbs that I had purchased anyway so I went to the auto parts store and had them hook up that diagnostic tool to see what the code was. The guy at the store said that it was my right side upstream O2 sensor. He mentioned that it might make the car idle oddly and affect gas mileage. I had been noticing for a couple of months that the car would occasionally idle slightly higher than usual ~1100 rpm instead of ~750. So I figured that I would just replace it myself. I got online that night and ordered the NTK oem part. That sucker was expensive $142 not including shipping, and I got the Haynes book to go with it. So $200 later I felt confident that I would fix my baby with my own two hands. Well the next morning I fired her up, and that stinking SES light went out.

So I have a couple of questions. Should I change the part even though the light is no longer on? How many of these O2 sensors does my car have? Can I be sure that I have changed the right one when there is no light to indicate that I have? Any extra input is great.

Thank you for any help. I used to work on my old Honda, and did it with flying colors, and a heck of a lot less money. I am less confident about my Mini. By the way it is an '04.

 

You have two O2 sensors, one before and one after the cat. I would hold on to the one you bought for now, since they really shouldn't need to be replaced until 100K.

Sometimes bad gas or something will trip the code, the light comes on, then after a while the code clears and it goes away.

I'd just watch it for a while. Try a bottle of Techron in each tank, does wonders for my '02.

 

How many miles do you have on your car? The O2 sensors are covered for 10 years/100,000 miles. I just got mine replaced at the Dealer for free. 05 S with 90,000 miles.

 

Just replaced my upstream sensor today with the Bosch model....$178. Car has 41k on it but has been tracked a decent amount these past 2 years. Maybe that's why mine went? I could clear the code and it would run fine but I thought might as well replace it since it's been tripping that code on and off for about a year.

 

Well you may be right, it could be the gas. I had been getting my gas from Sam's club, and went to Hess this time around...code cleared. Now that I think of it, it seems like the hesitations started when I started getting gas from Sam's. Still, I'll keep an eye on it and check with the dealer about replacing the O2 sensor for free. I like free.

 

Free is most definitely nice! Dealer visits are PITA to get to even tho they are only about an hour away. Mines not been to the dealer in about 3-4 years and not sure it will ever go back if I can help it.

I've been buying my gas at Citgo for all 6 1/2 years I've owned it except for any trips it's been on..

 

changing O2 sensors = not TOO hard.. if you can fit yourself under there.

my service engine light came on a while back.. code said o2 sensor bank 1 (upstream sensor).. ordered universal replacement.. had to butt connect it to the stock harness. changed both up and down stream while i was in there. no dice. light stayed on and comes back on shortly after reset @ auto parts store. still an issue..

BUT.. now that I've had some time to really chew on it... i'm pretty sure that the actual sensor itself wasn't the problem (since i made the mistake of sending it back to the seller claiming to have received a faulty part, then the replacement that came didn't work either)... when i pulled the wires i noticed that they had been pinched inside one of the clips that holds a heat shield in place. I'm now assuming that they were cut and/or shorted out by having been pinched in there. wouldn't be surprised if that became an intermittent problem, say like if the heat shield was pushing two worn sections of the wire together causing them to short out.

tonight's project: running new wires to the stock clip from the universal sensor.. wish me luck.

 

Try to use as few crimps as possible. Extra ones, plus extra lengths of wire, will change the Ohm resistance of the wire(s), and this affects the voltage the computer is reading.