2005 BMW X3 won't start after extremely cold weather. I replaced the battery and tried starting with spare key. The engine turns over but still won't start. It was running fine before cold weather. Any ideas on anything else I can try?
Your air intake temperature sensor (IAT) or coolant temperature sensor may be faulty or shorted to ground. The computer calculates the fuel delivery based on the outside temperature. Cold air is denser and requires more fuel. If the computer thinks it's 90 degrees outside when it's cold it won't deliver enough fuel to start the car. If you have a scan tool that will read live data you can check to see if the sensors are reading correctly.