I have an 09 R55 Mini Clubman with intermittent Downstream H2OS issues. I replaced the Downstream sensor a year ago and it started showing P0136 again.

Experience: I am an advanced user. DIY all day. I repair electronics. I have shop/autobody experience. Junk yard experience. I own my own tools and I own both the OBD MX+ and now an Autel.

Troubleshooting: (What did I do? What have I tested? What have I replaced.)

• I ordered a new OEM Downstream sensor and the issue continued. I cleaned the connector at the sensor and now I have a different code 002AF.
• I checked continuity on all 4 of the connector pins from the harness connector to the DME Connector.
• I am hoping it's not the DME. I ordered a KTAG just in case.
• I am tracing the power to the Downstream O2 Sensor and I wondered if there was a Fuse or a Relay connected between the DME and the Fuse Block.
• I found a the Mini O2 Sensor diagram but I need some clarification after looking at the BMW Advanced Vehicle Diagnosis PDF.
• I posted the following question on the Bimmerworld forum.

On the top left side of the diagram it says A6000 DME Control Module. Inside the box it says 87. This means its a relay right? Which relay does this refer to?

Is this an intentional error to prevent people from knowing what failed? For example an integrated relay providing power to the heater that is failing under the fuse block?

I made the following diagram using info I pulled together online.





Update: This report was after changing from a cheap OEM sensor to an NTK UP/Downstream Sensor. What component of the circuit am I missing here?