In the past month I have been plagued with a CEL that is periodic. It will come on and then go off several days later, then return after a few days. I have checked it out with a friend that has a garage and he told me that I had bad O2 sensors.

My question is how many of you have had this happen and is this a performance MINI problem. I'm hoping that it is not the catalytic converter that is going bad!

Cheers,

MeanGRN

 

Just had the pre-cat O2 sensor go out on my 04 MCS. Less than 20kmiles on the car . I do have the Milltek header & catback (19% as well as head/cam, etc). Car drove poorly (stumbled) when not at WOT, which is not too often .

 

Have you checked to see if a fault code has been generated? I don’t have the header, but I did have a bad pre-cat sensor. The code was P1030 and I had the SEL lit-up. After clearing the code it returned two weeks later.

 

I did have codes but I don't know which ones. Same thing happened to me. The CEL came back in about 2 weeks. I'm going to replace both just to be safe.


Cheers,

MeanGRN

 

I'm not sure it is the exact same problem but.......Miltek replaced the header

 

I've Miltek header & cat back for about 18 months. Worked fine for about a year or so then my SES light came on with code P0420 ( CAT below efficiency). Stratmosphere sent washers and said to put on rear 02 sensor to bring it out a bit. That worked for a week then same code back. Falcon (manufacturer of Miltek) send spacer from england said this would solve issue. The spacer screws in rear slot in header then sensor screws into this. Problem is that spacer puts rear 02 sensor out to far and it hits the body. Miltek sent new header with rear sensor position revised to allow the spacer to fit and not hit the body. The service from stratmosphere & Miltek have been absolutely first rate.
I've not installed header yet but will in few weeks and post here. I know at least two other folks that have had miltek headers for awhile and have recently experienced the P0420 code after long usage. Wonder if the Miltek CAT are failing like the others??

 

That is exactly the code that you had. He cleared the codes and it returned after a two weeks. The CEL will go off for a while but will return. Looks like I will be calling Stratmosphere in the morning!

Cheers,

MeanGRN

 

I am going slightly off topic here but I have a question about headers, Milltec in particular. I have a Milltec cat back and am very happy with it. I have looked into going with a header but was told that it is not advisable due to EPA laws regarding cat replacement legal issues. Input?

 

Milltek has had a problem with some cats on cars. Everyone I know has had them replaced without a problem. Pete at Stratmosphere has backed the product along with Milltek. 2 great companies.

 

Hello, I'm sorry to hear you guys are having similar issues with th OBD II P0420 error code. I have had an Alta header for some years now with no problems until now. The last thing I had done to my Mini was a dyno tune at BEHE performance. Now I feel that BEHE is a top notch shop in my area and, that they would know how to set my Air/fuel mixture settings correctly. Has anyone else had any problems with the Alta header? Additionally, my wife has driven my car but does not baby it like I do. One day while she had been driving she let the fuel level drop below the "low fuel" level stated in the manual, and I swear that is when the check engine light came on. My question is could this P0420 code just have been a temp code because the gas level was below the required level for proper operation? Or, is the Alta header failing. Any advice or prior experience with this problem would be appreciated. Thanks

 

I am getting the 0420 code with a 18 month old Milltek header that has seen a fair bit of track time. The code comes back when I clear it.

I've contacted Stratmosphere and waiting for their reply...

 

I've a Milltek header and catback, installed 18 months ago but car sees very limited mileage. No issues to date but interested in keeping up with this issue.

Oh! Thanks for giving me something else to worry about!!!!

 

You have to have a Bavarian Tech tool to clear those codes out or they will return

 

I'm not sure that is true. I had a P0420 and cleared it with my circa 2001 Actron OBD2 reader. I also replaced the original rear O2 sensor on my Milltek header with a NTK 25648 at the same time. No codes have returned.

 

Me too. I am clearing my codes with a Peake OBD reader:


So this might be a fouled sensor, not a header issue?

 

I can't directly say that your problem is the rear O2 sensor but since replacing it on mine, I no longer get the P0420 codes. Mine is a 2006 Milltek header that was installed by the dealer when we purchased the car new. I'm 99.9% sure that the O2 sensor that was originally installed in the header, and subsequently failed, was the original to the car.

 

I replaced the post cat sensor with an NTK sensor and I am still getting the P0420 code. I have emailed Stratmosphere 3 times and got no response. Time to call them and bug them in real-time...

 

Bringin' the thread back...

I have this same nagging issue with my car (04MCS, stratmosphere header/catback). I'll clear the code and it comes back. Lately it's been on pretty much all the time. I was going to try and use an angled o2 spacer. I'm really hoping to not have to replace the header/sensors but I do have 199400 miles on the car with original sensors...looks like it might be time.

From what I've read, Stratmoshere has closed their door.

 

I just blew out my second Miltek cat. My car makes 240HP. Apparently Miltek headers cannot handle this level of power.
I picked up a used RMW shorty header and that seems to be surviving nicely. Oh, sensors are only $90 on Amazon.com:

 

You have 200 000 miles on your O2 sensors and think they might be the problem! I think you should be thanking the gods that you have had such good service from them. I'd consider having them bronzed and hang them from the rear view mirror! Oops, is that sort of thing still done, dangit, showing my age yet again!
Cheers Ed!

 

Hey now, I've barely had to replace anything on that MINI. Still on the stock clutch too I'm really wishing I kept my stock cat and welded flanges onto it as a bolt in replacement.

Alright alright, I buy some o2 sensors today. Might help with the fuel mileage too. The 25648 sensor you posted, are you recommending that as a pre or post cat? The reviews seem to list it as pre-cat but earlier in this thread it's mentioned as post-cat.

 

Realoem shows same part number (11780872674) for pre and post cat O2 sensors.

 

It is the same pre an post.

 

Thanks guys, ordered. I'll post my results