The BMW N20 engine is a popular engine that has been used in a number of BMW models. It is known to be reliable, but it does have a few problems. The main issue seems to be with the turbocharger, which can fail and cause the car to lose power. Another issue that has been reported with the N20 engine is oil leaks. If you notice a leak under your car, take it to a mechanic as soon as possible. Leaking oil can damage the engine and can be expensive to fix.