BMW M340i Common Problems

In 2015, BMW released the replacement for its long-running 335i sports sedan, the 340i. The revised car continues to employ a turbo inline-six engine, albeit an all-new unit dubbed the B58. This new power plant delivers a boost in performance over the 335i, with even more power realized in the higher tier M340i.

Like nearly all inline-6 powered BMWs, the 340i is not issue-free. In this article, we are going to go over some of the most common issues on BMW’s high-performance 3-series so you know what to expect if you are in the market for one. 

340i Engine Problems

The B58 engine used in the 340i continues the line of turbocharged inline-six engines employed by BMW since 2006 with the release of the N54. Unlike the N54, and the same as the medial N55 engine, the B58 utilizes a single twin-scroll turbocharger (meaning the exhaust housing of the turbo is split into two veins, each fed by three of the six cylinders. 

While the B58 is a major improvement over its predecessors in terms of performance and reliability, it is not perfect. There are a few issues that plague these power plants, some of which have been present throughout the last 20 years of BMW inline-six engines. 

BMW B58 engine

Valve Cover Leaks 

The valve cover sits on the very top of the engine, covering the camshafts and valve train. A rubber gasket sits between the cover and the cylinder head, preventing oil from leaking out.  Valve cover oil leaks have been commonplace on BMW engines for years, and the B58 is no exception. 

More common on higher mileage engines, you should be on the lookout for valve cover leaks once your car hits around 60,000 miles. You might notice a slight burning smell, low oil levels, visible leaks around the valve cover, and in more severe cases, oil in the spark plug sockets. 

VANOS Solenoid Failure

VANOS is the name BMW uses for its variable valve timing (VVT) system. Actuated by oil pressure, the VANOS system can adjust valve timing on the fly, optimizing both power and efficiency depending on the situation. 

The VANOS solenoid is an electrical unit that controls the flow of oil to the VANOS system, allowing the valve timing to change dynamically as you drive. Infrequent oil changes can lead to buildup in the solenoid, causing it to not work as effectively. 

Additionally, the O-ring in the solenoid can start to leak, allowing oil to go where it isn’t supposed to, preventing the solenoid from working.

VANOS problems can be accompanied by sluggish acceleration, rough idling, a decrease in fuel economy, and even a limp mode condition. 

Oil Filter Failure

The paper oil filters used in the B58 engine are prone to shredding and breaking down even under normal driving conditions. A shredded filter can deposit paper in the oil filter housing, potentially causing larger issues and turning a simple oil change into a much more in-depth service. Oil filter failure can be attributed to a poor design (BMW updated the design of the filter) and improper replacement technique. Staying on top of oil services can reduce the chance of a filter failure occurring. 

Oil Level Sensor Issues

The 340i can sometimes give an inaccurate oil level reading, which is extremely concerning to owners. Inadequate oil can cause catastrophic engine damage very quickly, and on an expensive, performance-oriented vehicle like the 340i, this is a situation to avoid. 

Luckily, a frequent cause of the incorrect readings is related to a faulty sensor, not the oil level itself. With that being said, if you are getting an inadequate oil level reading, you should get your car towed to a shop immediately. The risk of running your engine without enough oil is not worth saving money by driving it to a shop. 

BMW Service in Ann Arbor

Orion Automotive Services is your one-stop for all things BMW repair in Ann Arbor. Our skilled and experienced technicians have the expertise needed to service your 340i. Whether you are looking for routine maintenance or in-depth diagnostics, our team has you covered. Call or schedule an appointment online today!

Book with our certified technicians today!


Book with our certified technicians today!