Bmw m6 Lambda Fault

[Al14hos]

Hello
Everyone, hope you are all well.
I need some help.

I have a bmw M6 2014 s63 cab.

Has downpipes and cold air intake fitted by me. And it’s been mapped once by a tuner but wasn’t happy with the map, but no faults.
I’ve purchased and swapped over to BM3, firstly had the stage 2 tune 93 no faults, then moved to stage 2 aggressive map and after a few miles I now have the engine light on and fault: 12B304
Heating lambda probe bank1, control: line break

Read by BM3 and also engine light on. I can clear it but it install re-appears.

After research I found (but I’m likely wrong) this is the lambda for the drivers side (UK CAR) downpipe. So I get a tested used one and fitted it but still have the fault. Have switched back to the stage 2 non aggressive map and have the fault.


Any advice would be great full, as I said I may not even be changing or looking at the correct sensor but when looking on the web (mostly m3/4 topics come up) with that fault and that’s the solution.

Look forward to your replies and in desperate need as I need an MOT.