The heater pipe problem in Volkswagen cars can be a potentially serious problem that, if left untreated, can lead to a variety of risks. If the heater pipe cracks or leaks, it can cause antifreeze to leak into the engine compartment, which can lead to a variety of issues. It can also cause the engine to overheat, which can lead to permanent engine damage. In addition, the antifreeze can enter the cabin of the car and cause passenger respiratory issues as well as lead to a slippery floor. If the heater pipe becomes clogged, it can cause the cabin of the car to not heat up properly, leading to passenger discomfort. Lastly, the heater pipe issue may cause corrosion in the engine, which can lead to further issues down the road.