i currently have this issue ongoing as well. the CCID tells me it's the left rear brake light assembly, but all bulbs are working fine, so i'm stumped.
'88 Porsche 944 - SOLD
'90 Audi Coupe Quattro - SOLD
'07 E90 335i 6MT - SOLD
'08 E90 335i 6MT - SOLD
'13 BRZ SportTech 6MT - current