Check engine light - O2S Bank 2 Sensor 1

[The_Hammer]

Hey everyone,

Sorry for posting about something that has been beaten to death. I searched through the other threads and couldn't get an exact answer.

My computer threw out a check engine light, it then went off after about another hour of driving and hasn't come back on since, which was 4 days ago. I checked the code, and it was the oxygen sensor from Bank 2 Sensor 1. My buddy (mechanic) then hooked up his tool to look at the sensor activity and they were cycling as normal.

So my question is basically is this sort of activity normal for these vehicles (I just got mine)? Do these often throw out phantom codes, in which case my O2S is probably fine? Or should I go ahead and replace the O2S even though the code went away and it appears to be working for the moment.

Thanks alot,

Mike

 

[Runnin'OnEmpty]

Mike, I suspect the O2 sensor is getting tired. When the MIL
comes on with an O2 code, and then goes off, it usually will
come on again eventually. This usually happens on long hwy
drives.

But since it's functioning OK now, I'd be hesitant in changing it.
I'd check the wiring to make sure it's not touching the header
and shorting out, and keep an eye on it.

The B2S1 is on the driver's side, closest one to the header, and I
believe it's fairly easy to access......

 

[The_Hammer]

Thanks for the reply. I pretty much gathered what you said. In that I would plan on replacing it if the code kept coming back. I was just kinda curious if it were like a querk of the explorer to spit O2S codes out or something of that nature.

 

[ak74]

I've had the Check Engine light on for a bank 2 O2 sensor for about 5 years now. For the first 4 years or so, it would come on and go off intermittently. During the cold winter months, it would stay off.

Just recently (starting this spring), it came on and hasn't shut off. I'm thinking about getting it replaced. Any idea what that should cost were I to take it somewhere for the work?

 

[The_Hammer]

Well I was searcing around for the best O2 sensors to use and the best prices. A mechanic friend of mine recommended the NGK NTK OEM replacement plug and play sensors. I found them on ebay for roughly 75 bucks canadian shipped to my door. Probably alot cheaper if you are in the states.

The bank 2 sensor 1 is apparantly fairly easy to change (I haven't done it). But the diagram looks like it is easy to get to. I recommend an O2 sensor socket instead of a wrench.

 

[budwich]

IF you indicate to us what the code(s) actually are, then perhaps another "interpretation" might be in order.

 

[The_Hammer]

IF you indicate to us what the code(s) actually are, then perhaps another "interpretation" might be in order.

The code is actually for the Bank 2 Sensor 1.

 

[budwich]

OOOOKKKKKAAAAYYYY but there isn't really a code that says "bank 2 sensor failed"... there are only codes that indicate a condition that code from "bank 2 sensor 1".... the "interpretation" of that condition is where your problem lies. Good luck though. As for question about sensors "randomly" throwing codes... yes... but usually its because of a condition sensed by the sensor and more than likely nothing to do with the sensor itself... but that's what the actual code would have told the forum.

 

[Runnin'OnEmpty]

Budwich is right, a specific code will allow a more precise
diagnosis. Your code will probably be a P0151 - P0155, so
if you can post it we can tell you more.

 

[The_Hammer]

Hmm...ok. I didn't really realize that there were multiple different codes which pointed to the same thing (Bank 2 sensor 1). One of my best buddies is a mechanic, so I just brought the X to his shop and he scanned it and said that the code was for the O2S from Bank 2 sensor 1 and that it was lazy and wasn't working up to par. But then he looked at the direct activity and it seemed to be cycling fine.

Thats all I really know. He didn't give me the actual exact code I guess because he didn't see it as necessary given the fact he told me what the code was.

I could always get him to rescan it and get the exact code. Would that tell much more than is already known?

 

[Dilbert5]

Ok without all the specifics, your mechanic friend said that the code was for a lazy sensor. I assume that the crosscounts were low. You did not indicate the mileage, but I quess that you probably have over 100k miles on the 98. If these are the original O2 sensors, then lazy O2 sensors are easy to believe, and I would put money that if the code will continue (althought the light might not be on all the time).

O2 sensors have a finite lifespan, if one is coming to the end of it's service life, they all are close. I would suggest that at the very least, you should replace both front sensors.

 

[The_Hammer]

140k km on the explorer, and I agree they are most likely original, I just bought this off the original owner who just had regular service at the dealer. So unless O2S is part of regular service schedule then they are original.

My mechanic also said that I will probably need to replace all of them soon, but he just suggested not to worry about it unless the code keeps coming back and the check engine light stays on. I'm planning a road trip with it in a couple weeks though so i'm thinking maybe it is worth replacing the fronts.

 

[Dilbert5]

I would not worry about damage to the engine, but the front two sensors can adversly affect mileage (since those are the one's that are used to adjust the mixture). I would suggest replacing them. I used universal bosch sensors. If you go this route, I would recomend soldering the connections and using heatshrink tubing.

 

[Amp67]

I just purchased front O2 sensors for both banks from Rockauto.com for something on the order of $30 each. I got that lazy sensor code also, it comes and goes. After 130K miles, I figured it was a good time to replace both sensors.

 

[coppe]

i´ve been dealing with this issue in my 2001 xls sohc for some months now, first it had more than one code, and after changing one o2 sensor, tune up, and other stuff...... i still have one code (po171 i think), this means that one bank is running lean. After doing all the troubleshooting (vacuum, maf, iac, egr, etc etc) the conclusion of my mechanic was that some part of the wiring from the computer to the o2 sensor was faulty, and i´m gonna take it to tha shop again when i get the time for it.

But what i´m saying, is that single bank codes are a pain in the butt to diagnose, it actually took me some money and like 3 visits to my mechanic to sort it out, if you wanna know if the problem is the o2 sensor, ask your friend to switch the connectors on both sensors, reset the codes in the computer, run it again, and wait for a code to appear, if the code has gone from po171 to po172 or the opposite, it means that the part at fault is the o2 sensor, since 71 is left and 72 is right or something like that. But if the code stays on the same side, or it does not reappear, theres something else wrong, and you shouldn´t spend the money on a new sensor.

Hope this helps.

 

[wow97]

help me drive me crazy

same problem here 97 explorer xl limited 4-door fulltime awd 4.0 sefi with 5-speed automatic i put all new owygen sensor new intake gasket new o-rings new egr valve and two egr sensor an d new maf sensor i reset my wife drive with her friends went away for week she said no problem for one week when she came back she light came back on i said son of ***** i got 30 p.s.i fuel pressure my dad check i said what the #### could the problem be 6years late light is stay on

 

[wow97]

same problem here 97 explorer xl limited 4-door fulltime awd 4.0 sefi colgne sohc v-6with 5-speed automatic i put all new oxygen sensor new intake gasket new o-rings new egr valve and two egr sensor an d new maf sensor i reset my wife drive with her friends went away for week she said no problem for one week when she came back she light came back on i said son of ***** i got 30 p.s.i fuel pressure my dad check i said what the #### could the problem be 6years late light is stay on