The SES on my 2003 was lighting up, code said one of the O2 sensors went out. I had it replaced, light stayed on (shop said they reset the code). The shop said it was a bad part. I took the car back to the shop where they replaced the new sensor with a newer one. Next day, the light is back on. Anyone have an idea what gives here? I am sick of taking the car back and forth to this shop. Gah.

 

Can you tell us what code you were getting on your car? Maybe the shop is misdiagnosing a defective 02 code with a lean code or something?

 

+1

An o2 sensor should be good for about 100,000 miles unless leaded fuel has been used....and unless the wiring is bad (perhaps chafed) and it causes it to not pre-heat (it is a 4 wire desgin on the MINI if I remember right), there is nor reason unless they got a dab of lube on the sensor that it would go bad.
Make sure you are dealing with a mechanic, not a parts changing monkey where you get your car fixed!! A code from the 02 sensor can tell you a ton of info...and usually just gives you a starting point on where to look for a bigger issue.
Which one of the 2 o2 sensors is giving you the problem....the pre-cat or the post cat sensor?
If all else fails, take a ride down to Atlanta (near the PDK airport) and have WayMotorWorks work on it!!

 

Parts Changing Monkeys FTL

 

Man, thanks a lot, guys. I believe it was the post-cat sensor-why do you ask, Zippy? My car is 100k + miles so it wasn't an unexpected issue. Also, despite returning my car with greasy door handles, these guys have been okay. In fact they have advised me against throwing money at problems in the past (i.e. unnecessary repairs).
I didn't ask about the specific code-they just said it ID'd the O2 sensor.
Also, thanks for the ATL shop pointer, though that's further than I'd want to go.
What's a "lean O2 code"?

 

A lean O2 code means your computer detected a low fuel condition. A stoich (balanced) air/fuel ratio is 14.7:1. The computer is designed to attempt to maintain this ratio until you press your pedal beyond 80%, at which point the computer goes into WOT mode and throws all the fuel it can into the engine. The lean code may be designed to go off at, say, 15.5:1, or perhaps 16:1.

If the sensor has been replaced three times, and the code continues to occur, you may have a bad gasket or other air leak that is causing excess air to get into the system. The air leak could occur in intake tubing or even at an exhaust gasket. In any case, the O2 sensor is detecting extra oxygen in the system.

 

Thanks, Jack,that's interesting. If it turns out to be a "lean" code, my bet is on the exhaust gasket. However, right now it appears to be telling the shop that the sensors aren't working. I'll check back after hearing the verdict from them.

 

Okay. The shop left a message saying they want the car back to run some tests to see if the other sensor is failing, thereby causing the new one to misread. I'm thinking second opinion? Don't want to pay for two of those things back-to-back just to find out its a computer error.

 

Second opinion would be good. Maybe they should have held onto the others that were already changed out. Both use the same part #.

 

I know there was a recall on the o2 sensor, my MINI has already had it replaced twice and it only has 35,000 miles on the clock. Do you know if MINI will continue to replace it for free in the future or at what point I'll be cut off?

 

This wouldn't be a Bosch aftermarket sensor would it? I have a supplier that sells an "OEM" sensor, or at least spec'd to be OEM. It's made by Bosch, has the correct plug on it....but just won't work. Swapped an OEM sensor and wallah. Problem fixed. Sensor would get lazy at idle. I verified this with an O'scope checking voltage directly and also watching it on OBD2 at the same time for redundant checking. O2 was a dud. BTW, this was the second Bosch sensor I tried.....

 

The recall was on some 04-05 cars...not a recall, but a warrenty extentsion to 10 yrs, 100,000 miles...
If the sensors went bad so fast, they should be warrentied by many places...not the labor, but the $$$ part should be free.
Mini parts are kinda $$, but somtetimes the extra 20% to get it working the first time is worth it!! Aftermarket should work, even the universal, where you solder the wires, but if you got one from a bad batch... The one on the shelf next to it might be bad, or perhaps counterfit too....

 

these o2 sensors scare me. My lean condition code tripped a year ago. I had a cracked header flex joint. I welded it back together and a month later the light went out. after smog last fall the code tripped again. now I am chaseing the problem. I don't want to pay a monkey and I also don't want to shell out 400 bones on o2 sensors. Then again I do have 130K miles and not one problem other than lean condition.

 

I thought the OP stated it was a post cat sensor replacement ? That sensor merely measures the health of the cat and is not related to fuel managment.

quote....."The SES on my 2003 was lighting up, code said one of the O2 sensors went out. I had it replaced, light stayed on"

Why are we thinking the engine is running lean again ?

Did the shop recommend that the cat be replaced ? Did they read the code correctly ? If it's a bad cat the 02 sensor is just doing it's job and was working fine right along.........

 

make sure they put in an OEM o2 sensor and not an aftermarket Bosch o2 sensor. the aftermarket one will still throw a code even if its new.
also try to get the fault code, because i've seen a bad map sensor throw an o2 code.

 

Okay, OP here. Both sensors were supposed to be OEM and nothing else. There was no talk of replacing the cat, thank goodness. So far what I have for sure is a SES light that keeps going off after 2 O2 installs (same sensor location). I scheduled an appointment with another shop with more experience with MINIS-I suspect from the majority of comments here that my car's computer just isn't letting go of the original error code. I'll check in with an update, and thanks for all the feedback!
Oh, and I could be wrong about the sensor location, but I think it was behind the cat.

 

 

Gray Raven, good point on the cat note. I missed that. That is a possibility.

gpwpat, good info. I have not familiarized myself with all the codes the Peake tool identifies/clears. Only condition I know of thus far that requires dealership clearing is the airbag sensor light.

 

Feel free to bring it by, but more importantly did they not clear the adaptations out of the computer?? If they don't do that, which takes BMW diagnosis software, the fault will never go away.
Also if it was a faulty part the OEM sensor carries a 2 yr parts warranty. Feel free to bring it to ATL if you need, I'm sure we can fix it.

WAY

 

My 05 MCS SES light came on a few months ago. I have an OBDII reader so- the codes are P0130 & P0136. Pre-CAT & post-CAT O2 sensors. So, I replaced them both at the same time. I purchased the Bosch universal sensors from Autozone at about $63 each. I'm now thinking I should have spent more $ & bought the OEM sensors. I can't get the SES lite to stay off. Every time I or others plug in the OBD unit, the codes read the same. I even took it to my local SpeeDee (Raynham, MA) where they have the expensive Snap-On diagnostics computer. They didn't find anymore than I did so- he didn't feel justified charging me (I went back with a case of beer for the 'boys'!- much appreciated). Reading down the possible fault list of both codes, it says: O2 sensor bad: O2 sensor wiring issue: lean/rich mixture: faulty spark plugs (changed them too); faulty plug wires (changed them also) & mis-fire. Well, none fit my faults as the MCS is running as it did 5-years ago. Even with 103k miles on her now. My next move: I'm going back to Autozone to but the OEM duplicate O2 sensors. If the lite goes out, the universal ones are going back for a refund (whether they like it or not- I printed all the relavent posts to put in front of the manage if I need to). I'll post again after they've been changed- again!

 

Did replacing the sensors with the OEM ones fix the problem?

 

I've gotten used to the warning light...I'm a high school teacher, keep putting this repair off until a long vacation break because I think it's probably a matter of a code reset that needs to be done on MINI software. In other words, no news from the OP.

 

In most cases, Autozone uses the Bosch brand as an OEM alternative to O2 sensors. You will more than likely have to order the correct replacements. If they cannot order them, you will have to go to an auto parts store that can. The actual replacement is NTK 25648. You can read more here (this thread references others; lotta reading but worth it): https://www.northamericanmotoring.co...-obd-code.html.

 

I took the car to a mechanic with experience with MINIs, who has MINI software. He says the cat forward sensor is now throwing a fault code. The forward one is also a Bosch, which means it was replaced at some point. I wonder if the first shop replaced the OEM sensor with the Bosch? Memory tells me the other mechanic replaced the sensor after the cat though. I'm going to replace the sensor, but now I have control arm bushings, CV axle and a belt tensioner to deal with...

 

Yep - my wife's 05 S convertible has the same issue. The shop replaced the O2 sensor at the last service, and a month later the light is on. The stinker in CT is that it's emissions time and they will not pass the beast with the CE light on no matter what they read on their equipment.

I had the battery unhooked (neg term only) to install a radio, but no luck in resetting the ECU.

Regards, Jim