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If your BMW is overheating, it can lead to severe damage to the head gasket, resulting in costly repairs that could reach thousands of dollars. The cooling system includes several crucial components, one of which is the water pump. This guide will walk you through how to identify a defective water pump in your vehicle, helping you save both time and money while accurately pinpointing the problem.

The first method to check if the water pump is defective requires no tools and can be done from inside the vehicle in a matter of seconds. This involves initiating a built-in test that comes factory-equipped with your BMW.

Open the expansion tank cap and check the coolant level. If low, refill with coolant and operate the engine watching the temperature levels. If refilling the coolant fixes the overheat issue, you're finished. If the expansion tank is full, continue reading.

Insert the key into the ignition and turn it to the position that powers on all the electronics, but do not start the engine.

Close the vehicle door and press and hold down the accelerator pedal for approximately 10 seconds.

Check the expansion tank for coolant recirculation. After pressing and holding the accelerator pedal for 10 seconds, the water pump should activate, causing the coolant to circulate in the tank, which can be identified by the movement indicated by the white arrow.

If there is no coolant recirculation, the water pump is not functioning properly and is defective.

The second method to checking if the water pump is defective is using a BMW scan tool to digitally read the pump RPMs.

Turn on the vehicle's engine and allow it to get to a steady idle and operating temperature.

Turn on the vehicle heater to the max heat temperature and fan level.

Using a BMW scan tool, read the RPMs of the pump. If RPMs equal 0 the pump is completely dead. If 1-30, the pump is weak and could cause intermediate overheating. If the RPM reads 70-100+, the water pump works perfectly fine.

Good job checking your BMW's electrical water pump functionality. If the water pump is dead, do not operate the vehicle until replacing it as this can cause thousands of dollars in repairs.