Car: '04 Mini Cooper S R53

Used a scanner and found out both my O2 sensors are bad. I tried swapping them out with some Bosch ones that had no connectors so I had to solder the existing connectors on. Reset the codes and results came back as both were still not working. I read on some forums that having an aftermarket exhaust sometimes makes these sensors go bad...not sure if it's 100% true or not. I currently have an MINI Cooper S R53 (04-06) Invidia N1 Titanium Tipped Catback exhaust on the car and was wondering what kind of O2 sensors would work best (other than from mini). All advice is greatly appreciated!

 

do you have an aftermarket header?

 

Not sure, bought the car used this is a link to the exhaust I believe is currently on the car. http://www.rallysportdirect.com/Invidia-N1-Cat-Back-Exhaust-Titanium-Tip-Mini-Cooper-S-2003-2004

 

The catback exhaust should have no effect on the O2 sensors or the converter or the codes.
The OEM brand NTK 25648 sensors tend to work much more reliably than the Bosch
ones, and that may be the problem. Alternatively, the problem could be with the
catalytic converter instead of the sensors, more likely with an aftermarket header but
it could happen with an 11 year old oem exhaust manifold/converter, too.
However, with a bad converter, the downstream sensor is usually the one that throws the code.
I'd bet on the sensors, first. If it is the cat instead, you'll still probably need the new oem sensors
at this point anyway.

 

Thanks for the info. Currently it's spitting out that both are bad I believe. Says bank 1 and bank 2. How would I know which converter I should get if it is bad?

 

The oem exhaust manifold to the back of the cat are sold as one piece and is pricey.
If you get just a cat, you'd have to cut the old one off and weld a new one on.
Another option is to get an aftermarket header with cat - but the good ones are as
pricey as the oem one, and some are not CARB approved and some aren't known for
longevity or quality of the cat. I have the Milltek one, which costs about $1250. Way
Motor Works sells this as well as the Flashpoint one (at under $800 currently). I chose
the Milltek as a performance item as I heard it has a good quality cat that will hold up for
more than a few years. Way says the Flashpoint header is a good value. See them on this page:
http://www.waymotorworks.com/02-06-cooper-s-r53/performance/exhaust

 

ive got a similar issue and it keeps blowing fuses. Did you find out what your issue is?

 

The 2004 MCS has one bank of sensors (bank 1) with 2 sensors. Sensor 1 is the pre-catalyst and the sensor 2 is the post-catalyst. Sensor-1 (pre-cat) provides a feedback loop to the ECU that controls the fuel mixture. Sensor-2 (post-cat) provide information of the catalyst converter efficiency. Both Sensors are the same part number. The Sensors have 2 circuits the Heater and the sensor. Both are checked at ignition"ON" for the proper resistance. If it does not pass an Mil code is set (codes P0130 - P0141). If both sensors are working but the CAT is defective you will probably get a code P0420 (Catalyst System Efficiency Below Threshold -Bank 1). You could also get the same code if the post-cat sensor (sensor-2) goes bad. What codes are you actually pulling? It is not to often that both Sensors fail at the same time. If the codes refer to the Sensor heaters check the fuse F03 located in the engine compartment next to the driver strut tower..... Good luck.


BTW. I have the same cat-back installed in my 2004 MSC for the pass 4 years. No issues.