This is important because your BIOS often tracks fan speeds to the CPU and may prevent the computer from booting if a CPU fan is not detected. You connect case fans to the motherboard, starting with the CPU_FAN label on your motherboard to your CPU fan. This causes the engine computer to miscalculate the amount of injected fuel, causing additional damage to your engine. The mass air flow (MAF) sensor, part of your vehicle’s electronic fuel injection system, is responsible for calculating the total amount of air entering the engine.