I have an 07 R56 base that we just changed the motor in, ran fine for about a week but check engine light came on and I'm getting a P173b error code, I pot a new coolant sensor in but still get the code. And the cooling fan runs for about 5 min after the car is shut off, even if you start the car and turn it right off again, anybody else run into this problem?

 

I just got the same problem.
Did you find an answer?

Thanks

Bill

 

https://www.northamericanmotoring.co...placement.html
you can try here. I currently have the same issue. About a month or two ago I had to replace the thermostat. Now I get that code and when I brought it to 3 different auto parts store to get it checked it came up with no result. After some looking into it it seems to have something to do with the thermostat and/or sensors that are related to that. I’m bringing it into the shop tomorrow to get it taken care of (hopefully), I’ll update with the results

 

xNickh8x,
Are you able to see your coolant temp when you go through the hidden stuff on the dash? Not sure on yours but mine is 7.0 CTMP-MOM. I'm going through same bit you guys are and wondering if a replacement CTS cures the issue. Have you tried unplugging your CTS and does the temp drop to like -040C or so? Can you please update in detail the result of your shop visit??
I have two DMEs/ECUs for my car and I can get the temp with one but not the other. Both show the 173B fault and I'm curious to know if it is stored on the DME or somewhere else on the CAN bus.

 

I couldn’t seem to find where it said the temp for that anywhere, however I did have inspection issues a few months ago where a couple monitors were ‘not ready’, and then like 2 ish months ago I had to replace the thermostat housing. So I can only assume that it has something to do with that. I went to the shop today and they said to go back tomorrow because their diagnostics guy wasn’t in today. So I’ll update here after that

 

What was the outcome of your shop visit? Was the diagnostics guy able to solve the problem? Do you know what he/she did/changed to fix it if so?

Search mini hidden codes on the web. With the key in and the door shut, hold the left button down on the digital speedo. When it changes, scroll to 19.0. Inter the sum of the last five digits of your VIN. This will unlock the hidden goodies and you can read/see what's going on with the sensors on the car. Scroll to 7.0 and you should see CTMP-MOM with a temperature displayed in Celsius. Hit the button again and 7.1 will show the outside air temp in C. On mine 7.0 shows ttt meaning the coolant temperature is invalid and the cars brain defaults to a overheat condition. It shows the outside temp just fine.
My hidden code explanation is crude. Again, search it and you will find the procedure in detail.