hi everyone I have a 2002 r53 Mini Cooper s and I was messing around with some friends the other day, putting the car around a little bit, and I noticed my engine light came on. So I came home and scanned it and got a p0131 code for bank 1 sensor 1. So I cleared it just to see what would happen, and yes it came right back on. But after I drove somewhere and then started it back up it was gone? Could this be a bad sensor or am I haveing a legitimate problem with air/fuel? I also can say at some points the car has a poor idle where it almost wants to stall. I also noticed I'm only getting like 23-24 mpg. I also noticed the car gives off a. It of a rich smell from the exhaust, and a bit of black soot in the exhaust tips. Only aftermarket parts (performance wise) are an invidia n1 exhaust and a K&N intake. If anyone has any ideas or suggestions, let me know, thanks!

 

Seems like a problem with ignition, gas not getting ignited, thus the rich exhaust you smell. Bad plug, wires, coil, hopefully one of those and not a leaky cylinder.

 

Well I'm pretty sure it's not the cool because I put a new coil on a while back. So I guess next step would be to replace the spark plugs, and then maybe do wires too. I thought maybe it was getting too much fuel but maybe I'm wrong.

 

If a cylinder if not firing, in essence, there is too much fuel if it's not getting ignited. Check to see if you have spark in that cylinder and do a compression test.

 

If you havent changed the front O2 sensor, i definitely would start there. change the plugs too, if they are real old (or at least make sure the gap is 0.035). My R53 kinda eats plugs, but i noticed a slight misfire/stumble at full throttle, no issue at idle. coils and plug wires rarely fail if not damaged. O2 sensors and plugs are wear items.

black soot on the exhaust tips is normal. the CELs will clear themselves after 3 startup/shutdown cycles IF the fault generating the code has not recurred in those 3 cycles.

 

Also, P0131 is "O2 sensor low voltage" which kinda means your O2 sensor is failing.....

 

I had the same problem on my 03 r53. intermittent O2 code. you'll notice as time goes on that it only occurs after you start the car again after erasing the code. If you can erase the code and it stays away for as long as you keep it running you'll know that it is the 02 sensor that needs replacing. Unfortunately you HAVE to go through mini to get the part. I installed an aftermarket by bosch and the code went away temporarily and then the same problem occurred. After reinstalling the new OEM part from mini I never have experienced this problem again. DO IT YOURSELF. it's super easy and takes about 15 min because its the front 02 sensor . Again, make sure you buy the part from mini. It should set you back around 225$

 

Yes, you have to use this one: NTK 25648. It is the exact one MINI uses. None of the substitutes will work (you will get a CEL).

I get mine here: http://www.autopartswarehouse.com/sk...L/NG25648.html

 

Rockauto has the same part for $95.

 

When mine went I had a huge drop in gas mileage:

https://www.northamericanmotoring.co...-readings.html