The BMW N20 is a turbocharged four-cylinder petrol engine which replaced the N53 and was produced from 2011-2017. Although the N20 is a four-cylinder engine, it is considered a replacement for the naturally aspirated six-cylinder N52/N53 because it powers equivalent models, producing similar horsepower to the N52/N53 with greater low-rpm torque and better efficiency. The N20 features a twin-scroll turbocharger, double-VANOS, Valvetronic, direct injection, automatic stop-start and an electric water pump. The N20 was sold alongside the smaller displacement BMW N13 turbocharged four-cylinder engine. The N20 was placed in Wards Top 10 Engines in 2012. In 2014, the N20 began to be replaced by its successor, the BMW B48.
It has been well documented in online forums, including www.bimmerpost.com, that thousands of early production N20 engines were manufactured with faulty internal plastic timing chain guides. Evidence indicates that defective polycarbonate compositions were utilized in the manufacturing process for the timing chain guide, and as a result over a very short period of time the rigid plastic guides would break down and deteriorate in the engine with little or no warning. Upon failure of these internal plastic components, the timing chain slackens and "skips time" by jumping teeth on upper cam shaft sprocket, a phenomenon that causes catastrophic damage to the engine by un-synchronizing the cam shafts and valve train. In 2017, a class action lawsuit was filed by several owners against BMW seeking redress for the faulty units. Plaintiffs in the BMW engine defect class action seek to represent a nationwide Class of consumers affected by timing chain guide and secondary chain failure and wear as well as several subclasses for states such as New Jersey, Illinois, Florida, Utah, New York, Colorado, Texas, Alabama, Oklahoma, Massachusetts, California, Wisconsin, Oregon and North Carolina. In 2018 BMW attempted to dismiss the class action lawsuit. In 2019 U.S. District Judge William H. Walls partially granted and partially denied BMW’s motion to dismiss claims that it sold vehicles with a known engine defect. Walls also ruled that the automaker cannot escape the suit entirely.
