Hi there,

I had a shop install a Milltek exhaust on my Mini today. While on my way back and listening to the beautiful new sound, I noticed the check engine light was on. AdvanceAuto ran the codes and said it was an 02 sensor throwing the light on.

Do you think the install may have ruined an 02 sensor? The two bolts holding the exhaust to the catalytic converter were severely corroded thus they had to use a torch to cut them off. Those two bolts are not far from the 02 sensor.

How do I tell that I need a new 02 sensor versus just giving the cpu in the car time to adjust to the new system.

Thanks, Cody

 

You can clear the code and see if it comes back although unless they blew a bunch of junk into the sensor, not sure why it would send a code.

 

Make sure the sensor wires are not leaning against heat shield or pipe, I had a strange o2 sensor code that would not go away almost bought a new sensor. Got to looking around down there and saw the wires leaning on heat shield, moved them, cleared code and it has not come back.

 

If it is a bad O2 sensor, keep in mind that MINI issued a notice a couple of years back that faulty O2 sensors would be replaced up to 100,000 miles as I recall. Do a "search" for particulars.

 

maybe post the code if you know what it is.

i recently had this problem too after instaling a header and high flow cat.

ended up needing a new upstream/pre-cat o2 sensor. dealer will charge you $200 but you can get one on amazon for $90. just make sure it is the right oem NTK brand replacement part #

 

I fixed the issue yesterday. After having the computer reset and the same codes coming up soon after, it was decided that the downstream O2 sensor was bad. I got the Bosch sensor off of Amazon for $80 - good deal after pricing them in AdvanceAuto! I replaced it, had the computer reset again, and now she is good to go and will hopefully pass VA inspection!

I don't remember the exact codes, but when the computer was ran the first time, two codes showed up; one of course for the O2 sensor, and they said the second was something dealing with the throttle body. That particular code was only shown in the European codes, and not in the American. Weird? As of now, no service light is on and I'm happy at that. The car seems to be running okay, and I haven't noticed anything weird in the throttle. That's a problem for another day as I've spent enough money as it is. Any ideas of what this might be, though? Is there a know issue with the R53's throttle body?

 

typically when an o2 goes bad, it will throw a couple other codes with it since it is closely related to the ECU, air/fuel, etc.

mine did the same. it was most likely it was just tricking the ecu into thinking something else was wrong due to the incorrect readings it was sending.

if the code for the throttle body does come back, i would suggest cleaning it out before buying a new one, as if i recall correctly they are upwards of $150 and to clean them, you just remove the air intake tube... get some carb cleaner, spray the top, wipe, hold the buttterfly open, spray, wipe... thats a quick way to do it without removing it. not as thorough, but youll def clear up some carbon.

lastly, the bosch will work for the downstream sensor, but ive read just about every thread on here about o2 issues, and its 100% that if you need to replace the upstream sensor, get the NTK brand part (again can be found on amazon). i guess sometimes the bosch and other brands are finnicky and sometimes will throw codes.