Need help! Instrument Cluster Failure?

[Texoma1836]

My 2012 started fluctuating between -40 and +122 degrees Fahrenheit on the dash. This was annoying so I took it into the dealership and had them replace the ambient air temperature sensor. That fixed the problem for about a month, and then it started happening again as I went on a drive one Sunday afternoon. The temp would be at -40, then it would fix itself, then it would be at 122, then it would fix itself, back and forth and back and forth, then suddenly as I was going down the highway, it went into limp mode and threw P0073 (Temp variation between ambient air and charge air too great) and P10B0. I limped home and let it sit for a while. Finally, the ambient temp went back to the correct temperature (101 degrees). The car came out of limp mode and I took it to the dealership without issue.

At the dealership, they initially tried to pin the error on my recent installment of an Active Autowerk's charge pipe (my second plastic one had blown off recently so I wanted to go all metal). The mechanics finally confirmed that I had installed the aftermarket pipe correctly so they couldn't fault me for that. They replaced the ambient air temp sensor again under warranty since apparently the last one had failed in less than a month. I go to pick it up and WHAM; -40F before I even drive off from the garage bay. I turned right around, told them it wasn't fixed so they took it back. A week later, they tell me that the instrument cluster pins need replacing after they determined that the second ambient temp gauge is working correctly and they could not identify any shorts in the wiring harness. Okay, I said. They replaced the pins. I get the call - that did not fix it. So, now two weeks without my car, they finally call a master tech who tells my service advisor that I have a "faulty" instrument cluster and that the whole thing will need to be replaced at a whopping $1500.

I'm really confused about this? I don't understand what kind of error or fault the instrument cluster could have to cause this to happen? Everything else works perfectly fine. All gauges work and the display works. But you mean to tell me that the instrument cluster just randomly causes the ambient temp to be reported incorrectly at random times and that it has nothing to do with any kind of electrical short or any kind of sensor malfunction? And apparently this error is not just a visual one too as it is reporting the incorrect temperature as the actual ambient air temp to the ECU, enough to shut the car down.

Personally I have a hunch that the master tech also didn't know what was wrong and that they were out of ideas so they said screw it, just replace the whole thing. What are y'alls thoughts?

[NorthernDancer]

I tend to agree with you but you are fighting this alone. My best recommendation is to join BMWCCA which will give you immediate access to tech guru/editor Mike Miller plus technical Service Advisors, plus Ombudsmen.

And, I just see that Tejas Chapter of BMWCCA is right there in Austin. www.tejaschapter.org