NHTSA Complaint #11092160 — 2012 BMW X5

THIS PAST WINTER THE CHECK ENGINE LIGHT IN MY 2012 BMW X5 DIESEL (X35D) CAME ON. CHECKING THE CODE (4BCC) REVEALED THAT FILL SENSOR FOR THE PASSIVE DIESEL EXHAUST FLUID (DEF) TANK IS MALFUNCTIONING. I HAD LETTERS FROM BMW STATING THAT BMW HAD EXTENDED THE WARRANTY ON THE ACTIVE DEF TANK AND NOS SENSORS TO 10 YEARS AND 120K MILES BUT NOT ON THE PASSIVE DEF TANK. CHECKING VARIOUS BMW FORUMS I FOUND THAT IT IS A VERY COMMON FAILURE. MANY PEOPLE ARE REPORTING THIS AND SO MUCH SO THAT THERE IS A CANADIAN COMPANY (XEMODEX) THAT IS MAKING BETTER VERSION OF THESE PARTS AND PROVIDING MUCH LONGER REPAIR WARRANTY THAN BMW PROVIDES. ONE OF THE MEMBERS IN THE COMMUNITY ACTUALLY DID A THOROUGH ANALYSIS WITH SCOPE (HTTPS://WWW.YOUTUBE.COM/WATCH?V=XFAL06PD_PG) AND IT SHOWED THAT THE FILL SENSORS USED IN THE ACTIVE TANK IS A THREE LEVELS READER AND IN THE PASSIVE TANK IS A TWO LEVELS READER AND THE ONES THAT GO BAD IS USUALLY THE HIGHEST LEVEL FILL MARKER WHICH BECOMES DRY EARLY ON IN THE USAGE CYCLE. IT APPEARS THAT THERE IS A SYSTEMATIC ISSUE HERE WHERE THE DEF HEATER AND LEVEL SENSOR ARE ALL HOUSED TOGETHER AND DURING WINTER TIME WHEN THE DEF HEATER COMES ON IT CAUSES THE UNSUBMERGED PART OF THE FILL SENSOR TO GO BAD. THE OTHER ISSUE IS THAT CURRENTLY MY PASSIVE DEF TANK IS FILLED WITH DEF BUT BECAUSE OF THE FILL SENSOR MALFUNCTION IT IS NOT ALLOWING FLOW OF DEF FROM PASSIVE TANK TO ACTIVE TANK LIMITING MY RANGE OF TRAVEL BEFORE THE SYSTEM WOULD NOT ALLOW THE VEHICLE TO START DUE TO ACTIVE TANK BEING EMPTY. AND THIRDLY, NOT SURE WHY A PASSIVE TANK WAS INTRODUCED WHEN MAKING THE ACTIVE ONE SLIGHTLY BIGGER WOULD ACCOMPLISH THE SAME THING AND AVOID USE OF TWICE AS MANY OF THESE FAULTY PARTS AND DESIGN. BOTH THE ACTIVE TANK AND THE PASSIVE TANK USE THE SAME FILL SENSOR AND HEATER COMPONENTS BUT THE WARRANTY WAS EXTENDED ONLY ON THE ACTIVE THANK AND NOT ON THE PASSIVE TANK.