Q: P0170 and P0173, I have changed the MAF and Both sensors. Now my car does not start.

P0170 and 173 indicate that your fuel mixture is off. The ECU tries to compensate, but the error is so large that it cant make the correction. It can be caused by a Mass Air Flow sensor, but there could be other causes as well. Air leaks are a possibility, which you say you have investigated, and there could also be a problem with fuel pressure. When you say the car is clicking I wonder if your engine is cranking at all. It could be that the battery voltage is down. If you have not been able to start the car because of a battery problem, there is no way of knowing whether the MAF that you installed will solve the problem. Replacing parts until your car starts can get very expensive very quickly. Your best bet is to go ahead and get a thorough diagnosis. By contacting Your Mechanic, you can have a technician come to your home or office and check out your BMW and let you know what it’s going to take to solve your problem.