This is what your IHKA is supposed to look like.

 

Well. This is what came with the car 8 years ago.

 

PM me your VIN. I'll look it up to know for sure. If it's not originally what came with the car it's the reason you have that error message

 

Not sure why this picture didn't post earlier. Here's the controls that came with the car.
If this wasn't supposed to be installed, why haven't I had an auxiliary pump fail code until now?
I'm wondering if the main pump is going out.

 

That error could be a red herring. What device are you using to read DTC codes?

 

I have an Autel Bluetooth reader for BMW as well as an Icarsoft for BMW.
I do not have the big bucks for the BMW certified computer programs.

 

Looking at your VIN you have option code S534 auto A/c dual climate so your IHKA should look like the below. Although this is not the reason why your heat is not getting hot anymore. I would say that the thermo is stuck open and you need to replace it. You can check that by looking at live data to see if the car is getting up to operating temp. If it's not its your thermo and I never replace a thermo on cars like yours without doing the pump also due to the nature of uninstalling it.

 

Thanks! I'll check that out and agree about replacing pump too. I've done this job on my wife's E61 wagon last year.

 

North American cars only have IHKA-High (Auto Climate,) on E60/61. The functions changed several times over the life of the model, but always automatic. The basic climate system was only available in other countries. My guess, without seeing the error, is referencing the 'water pump.' AUX or otherwise. There was no standby heater shipped to North America either.

True AUX water pump is typically attached or directly adjacent to the heater control valve.