I have a 2015 Mini F56 base model approaching 90,000 miles that gave me a P0053 error (upstream O2 sensor). I cleared the error, but the error returned after a couple of drives.

I plan to replace the upstream sensor, and feel I might as well replace the downstream sensor at the same time.

What is the easiest/most effective way to access the sensors? I have searched online and found two different approaches described in a Mini F56 workshop service manual.

The first (B38A.pdf) seems to suggest it is for cars with the B38A engine and simply removes the clean air pipe to provide access to the O2 sensors.
The second approach (F56.pdf) does not appear to indicate what engine applies, but removes windshield wiper arms, cowling, the upper firewall bulkhead, and the clean air pipe.

 

Had to order sensors online as none of my local shops had the downstream sensor in stock.

Replaced them today - basically following the approach entailing removing windshield wiper arms, the upper firewall bulkhead, and the clean air pipe. I found I did not need to remove the cowling under the wipers. I was not sure how to get the cowling off from under the wipers and did not want to break it, but I was able to flex this enough to remove the upper firewall bulkhead and the clean air pipe. I could not find a way to fit my torque wrench onto either O2 sensor in the limited space, so just snugged them tight with an open end wrench.

 

I ordered both (Bosch) from Pelican Parts

 

The B48/B46 need the cowling removed in order to remove the clean air pipe, The B38 does not.