It’s hard not to like a motor that produces 300 horsepower, 300 ft lb of torque and is silky smooth as only an inline six can be. When BMW rolled out the 3.0 liter, twin-turbo N54 motor in the 2006 335i, it helped move a lot of inventory from BMW dealer lots. Some saw it as a poor man’s M3, although “poor man” and BMW are somewhat contradictory terms. The motor proved to be so good that BMW bolted it into 1 series cars, 3 series cars, 5 series cars, the Z4 roadster and the X6 crossover. In other words, the N54 has become a fairly common motor in BMW’s product mix.
That may turn out to be bad news for BMW, as a California law firm has filed a class action lawsuit against BMW for alleged defects in the N54 motor. The lawsuit targets two common problem areas: failure of the high pressure fuel pump, and loss of power from the twin-turbochargers, especially after a BMW software update is installed. According to the suit, the software update inhibits performance of the twin-turbos, increasing turbo lag and creating a noticeable performance deficit.
The ultimate goal of the suit is to prompt BMW into a full recall of N54 equipped models. Should the high pressure fuel pump fail, the car can still be driven in a “limp home” mode, but with greatly reduced power and acceleration. The suit alleges that this can create a dangerous situation for a driver, greatly increasing the risk of an accident. It’s also worth noting that this isn’t the first lawsuit filed against BMW for defects in the N54 motor.
BMW has acknowledged problems with the high pressure fuel pump on N54 motors, and is extending the warranty to 10 years or 120,00 miles on this component. The company has not addressed the reduction in power following the software update, but Autoblog quotes BMW spokesman Matthew Russell as saying, “In an effort to address specific noise concerns, BMW updated the turbocharged engine software on 335i/xi and 535i/xi models built from June 2006 through March 2008. The updated software causes a small amount of increased “turbocharger lag” under certain circumstances and, while not substantial, the lag may be perceptible to the most sensitive BMW drivers.”