Do Oxygen sensors typically go out in pairs?

P

phil123

New member
I've got a 2003 V6 with about 56K miles on it. This past weekend the check engine light came on and Autozone told me it was my passenger side front Oxygen sensor. So I replace it, reset the computer and the light comes right back on with a code P2238 O2 Sensor Positive Current Control Circuit Low - Bank 1 Sensor 1. Now this appears to be an issue with the driver's side front oxygen sensor. I don't know much about emission systems, but I'm wondering if there is some underlying issue that could be causing this. From what I've read, these things don't typically go out in pairs. I'm a little hesitant to continue replacing these sensors as expensive as they are if the issue could be something else. I'd like to avoid being bent over by the dealer, but I'm not sure how else do deal with it. Any suggestions? It seems to be running fine and there has been no decrease in gas mileage, but I certainly want to get it fixed.
 
Last edited:
Register to hide this ad
Put the old passenger side sensor on the drivers side and see what happens. They typically don't fail together and you might have replace the wrong one. Also check the wiring for any issues.
 
generally they dont go out in pairs...

Though it sounds like their might be a deeper issue to research with all this.
 
On my '04 V6 one driver's side sensor failed, then after it was replaced, about 2 months later one sensor on the passenger side failed. Thankfully it was under warranty.
 
O2 sensors degrade over time - they become less responsive. I would bet that if you replaced all of your O2 sensors at 56,000 miles you would see some improvement in your vehicle's fuel econonmy and its part throttle responsiveness.

If one has gone bad at this mileage, replace them all.

Maybe the ECU is comparing the performance of the other sensor to your new one, and has decided that the other one isn't measuring up?
 
Last edited:
The oxygen sensors are only used during cursing speeds; not for accelerating, decelerating, or when the engine is not up to temp. Replacing them all will cost a small fortune. The downstream ones have nothing to do with performance, so never replace these unless they go bad. They are around $ 150/ea at the dealers.
 
O2 sensors ARE used during part throttle acceleration, but not during wide open throttle acceleration.

O2 sensors become active well before the engine has completed warming up - they have their own heating element to bring them up to operating temperature very quickly.

The O2 sensors downstream of the catalytic convertors are used only to monitor the function of the convertors, so greasefingers is right, it probably wouldn't be useful to replace those early if your ECU doesn't mind them.

You can generally find the O2 sensors for a lot less than $150, and replacing them is not difficult - though they do require a special socket because of their wires.. I don't have any personal experience with Toyota O2 sensors, though.
 
A good summary of information on this subject can be found in the Bosch Automotive Handbook.

You can also learn a lot by using an OBD-II scanner while actually operating your vehicle.
 
Alright, I decided to take the good O2 sensor from the passenger's side and swap it with the driver's side that was giving me the P2238 error code. Once I swapped the two I disconnected the battery to reset it and the light came right back on. I went back to Autozone to check it and the error code was P2241, which is the passenger front O2. So I thought I had isolated the problem and I bought another O2 sensor. Replaced the passenger front sensor, reset it, and the light comes back on immediately. Took it back to Autozone and now it is throwing both error codes P2238 and P2241, which is both front O2 sensors.

Has anyone ever heard of having to drive for awhile after the O2 sensor replacement to make the check engine light go off? Sounds like BS to me, but the guy at autozone said sometimes you have to drive 100 miles before it goes off.
 
greasefingers said:
Have you cleaned the MAF sensor yet? If not then do it.
Click to expand...
:iagree:

I recntly went through a lot of trouble to replace the two front O2 sensors on my mothers' Mercury Mystique because it was throwing a code for them. For some odd reason just after that it the cel came back on and gave me a code for the EGR, so I changed that but the cel or the code did not go away. I then cleaned the MAF with the CRC MAF cleaner and all was good from then on. I bet if I would have tried that first I would have solved my problem much easier and less expensively.

As a side note after this episode and repalcing the transmission she traded it in on a '07 Corrola. :bigok:
 
phil123 said:
Has anyone ever heard of having to drive for awhile after the O2 sensor replacement to make the check engine light go off? Sounds like BS to me, but the guy at autozone said sometimes you have to drive 100 miles before it goes off.
Click to expand...
Yes it's called an OBD drive cycle.

More info here = http://www.obdii.com/drivecycleford.html *

* Yea I know it's a Ford Site but the procedure is similar for a all OBDII equipped vehicles.
 
Cleaned the MAF sensor and had Autozone reset the computer. CEL came back on within 2 minutes. Not sure what else to do, so I made an appointment with the dealer. I'll post the outcome.
 
You must log in or register to reply here.

Members online

Total: 935 (members: 2, guests: 933)

Forum statistics

Threads
278,312
Messages
3,554,089
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top