BMW N55 Common Problems

The N55 was introduced in 2009 as the replacement for BMW’s first mass-produced turbocharged engine, the N54. The N54 was widely known for its potent power, but also the various issues it would commonly experience. 

Building its successor, BMW focused on maintaining the smooth straight-six feel and turbocharged punch of the N54 but also went to work on fixing many of the problems that plagued it. The N55 would ditch the twin-turbos for BMW’s first “twin-scroll” turbo, or one turbocharger with the exhaust side split into two channels (or scrolls), accomplishing a similar effect without the reliability issues of twin-turbos or significant lag of large single turbos. The N55 also saw the addition of Valvetronic, a variable valve lift system that was absent on the previous motor. 

While the Bavarians patched up some of the N54’s biggest failure points, the N55 is still a complex German engine that’s bound to develop issues from wear and tear over years of spirited driving and regular use. Here are some of the most common problems to watch out for on the BMW N55!

Common Problems with the BMW N55 

Charge Pipe Failure

The charge pipe setup on the N55 is made of plastic, which while durable from the factory, becomes brittle over time due to temperature fluctuations and old age. When the plastic eventually cracks, the engine won’t be able to sustain the boost level requested by the ECU. This condition will result in a drop in power. A similar failure can occur when the metal clamps connecting the pipes fail. 

Faulty Water Pump

Water pump failure is an issue not exclusive to the N55; a lot of BMW engines struggle with this issue. A large reason for this comes from BMW’s use of electric water pumps, which experience faster failure than their belt-driven counterparts. 

A bad water pump can be catastrophic to your engine, as the coolant is no longer being pumped around the engine. Without proper cooling, your motor will build up a dangerous amount of heat and eventually warp or crack the sensitive internal components. Overheating will lead to irreparable engine damage if not addressed as soon as possible.

Cutaway of BMW electric waterpump
Image Courtesy of BMW Group

Valve Cover Gasket Leak

This same issue was also present on the N54, but the N55 did little to mitigate it. The valve cover gasket sits between your cylinder head and valve cover, creating an airtight seal to keep oil within the system. 

The rubber gasket is exposed to constant high temperatures and pressures, causing leaks to form over time. This can cause the oil within to leak externally, depriving your motor of lubrication and cooling while also dripping onto hot engine components below. In some cases, the oil may leak down and coat spark plugs, causing misfires that can further damage your engine.

VANOS Solenoid Failure

VANOS solenoid failure is far from an unseen issue on BMW engines, and that holds in the N55. The solenoids are responsible for regulating the oil pressure used to control the helical gear within your VANOS system, actuating the variable valve timing.

The solenoids rely on rubber o-rings to keep the seal airtight, and when these seals are exposed to high heat and constant use, they can begin to deform or crack which allows an unregulated amount of oil to enter.

VANOS solenoid failure can result in issues such as loss of power, sluggish acceleration, reduced efficiency, rough idle, or your vehicle entering limp mode to protect itself. 

High-Pressure Fuel Pump (HPFP)

The high-pressure fuel pump is responsible for moving fuel from the tank to the injectors, which inject directly into the cylinders. HPFP failure mainly affected N55s from the 2010-2011 model years, where it experienced similar failures to the N54 HPFP issue that led to a lawsuit in 2009. 

Post-2011, BMW finally, after multiple attempts, fitted the N55 with a properly dependable high-pressure fuel pump. While most affected models have likely already had their HPFP replaced, it’s still possible that early N55s with the OEM pump will experience failure. 

BMW high pressure fuel pump
Image Courtesy of BMW Group

BMW Services in Carlsbad

If you need service or repair for your Bimmer, trust the experienced Euro technicians at Carlsbad Auto Service! Our team has the expertise and equipment to properly take care of your BMW, no matter the issue it’s experiencing. Whether you just need routine maintenance or are experiencing one of the above issues, give Carlsbad Auto Service a call or schedule online today!

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