I have a 2006 530i that I believe needs the thermostat replaced. I'm not getting any heat from the vents, just blowing cold air. My car doesn't have a temp gage but I did check the engine temp by using that ridiculous code nonsense on the dash display. I can't get the car over 83 Celsius but the thermostat calls for 97 Celsius. Here's my problem: I ordered the thermostat online and when I received it, it looks nothing like the one on my car. I suspect that because my car has a September 05 build date that it may call for an 05 thermostat but those years offer two options. One is the one I ordered and is wrong, the other looks similar to what I need. The different thermostats are for different engine codes. One for an N52 and the other for an M54. My question is: how do I determine my cars engine code??? Any help would be greatly appreciated. Thanks, guys.