BMW had a challenging task in developing a successor to the acclaimed E46 chassis. The E90 was a completely redesigned 3 series that debuted in 2005 and remained in production until 2013. It had various engine options, body configurations, and trim performance levels.

See our post on Common BMW E46 Problems

Overview of the BMW E90

The E90 platform was reliable and accommodating. BMW’s first gasoline-powered turbocharged engine, the N54, fuel-efficient diesel, and high-performance V8s. E90 3-Series sedans, wagons, coupes, and convertibles were offered in all-wheel and rear-wheel drive  (E93).

The Most Frequent Mechanical Problems

While the E90 platform was generally reliable, it did share several faults with other BMW models. Several of these problems are more widespread today because of their advanced age. You should be aware of these issues if you plan on purchasing a used E90.

Oil Leaking

BMW E90s often leak oil in three primary places. All six-cylinder engines from that period have these issues. Inadequate maintenance will cause leaks in the oil pan, oil filter housing, and valve cover gaskets.

If you ignore a leaky oil filter housing, it might cause catastrophic failure. These inline-six engines have the housings mounted above the motor, above the serpentine belt. The belt and other parts are lubricated with oil as it seeps out. Eventually, this will lead to the serpentine belt slipping off the pulley due to premature wear. Worst yet, the belt may be drawn into the crankcase via the front crank seal. The engine might be severely damaged if this occurs.

By changing the oil at regular intervals (recommended every 8,000 kilometers) and inspecting potential leak points at each service, you may head off expensive repairs in the future.

Issues with the Ignition Coils

BMW E90s often have problems with the ignition coils that ignite the spark plug. A misfire is the result of a malfunctioning ignition coil. Moving the coil to a different cylinder and seeing whether the misfire persists is a simple approach to determine if it is defective.

Problems with the VANOS Solenoid

BMW’s valve timing is changeable thanks to a technology called VANOS, which is controlled by a pair of solenoids. Oil sludge deposits might impede these solenoids. Low engine power and warning light are symptoms of a malfunctioning VANOS system.

E90 Engine Problems

BMW’s first production turbo petrol engine, the N54, was introduced for the E90 generation. This engine had its own set of problems, and since it was so prevalent in the E90 series, we’ve dealt with them individually. It’s important to remember that the N54 is susceptible to the same widespread problems that plague other vehicles, such as oil leakage and ignition coil problems.

Fuel Injector Problems

BMWs from the E90 generation with the N54 turbocharger inline-six engine have Piezo fuel injectors. When electricity is given to a crystalline substance, a tiny expansion occurs, a phenomenon known as piezo (short for piezoelectric). Piezo injectors use this effect to provide finely regulated fuel delivery.

While this technique was more accurate than the injectors used in most motors then, it was prone to breakdowns. Over-fueling occurs when these injectors malfunction, triggering rich error codes, misfires, and eventually damaging the catalytic converters if the problem isn’t fixed.

Turbo Fail

BMW’s N54 engine was the automaker’s first mass-produced turbocharged unit. This motor’s high power output (thanks to its factory-forged internals) makes it a favorite among enthusiasts, even though it is notoriously problematic in its normal state. These engines have wastegate issues with their turbos.

The start-up will cause the wastegates to make a distinctive rattling sound. Low boost faults will occur if they don’t stay closed for a while. As the wastegates are broken beyond repair, a new turbocharger assembly is required.

Accumulated Carbon

Carbon buildup is problematic for the N54, as it is for many direct-injected turbocharged engines. Over time, carbon deposits on the intake valves’ rear sides might reduce their efficiency. A common technique for removing carbon deposits from these motors is walnut blasting, which entails blowing rough walnut shells through each intake port while the valves are closed.

E90 HPFP Problems

BMW E90s often have problems with the HPFP (high-pressure fuel pump). Faulty internal seals may cause pump failure.

Problems unique to diesel engines

BMW E90s may be purchased with either a gas or diesel engine. Vehicles like the 335d improved fuel efficiency compared to their gasoline rivals while still providing enough performance.

Complications with the Emissions Management System

There wasn’t a lot of failure rate with the diesel engines themselves. Still, the emissions systems inside the exhaust were so problematic that BMW had to issue extended warranties on several components.

The DEF/SCR Tank

Injecting diesel exhaust fluid (DEF) into the exhaust causes a reaction that lowers NOx gas emissions. As the DEF tank’s sensors often fail and are not repairable, they must be replaced entirely.

The Diesel Particulate Filter

It is possible for the diesel particulate filter, which is in charge of removing big particles from the exhaust, to get blocked. Symptoms include no power, dashboard lights, and a lot of smoke.

The EGR System

Whilst the EGR system seldom fails on its own, problems might arise over time from accumulating soot.

Diesel engine maintenance and repair for an E90 is both costly and necessary.

Yet, failing an emissions test is much more costly than replacing the broken parts.

Non-Mechanical Problems

Certain E90 BMWs had issues that had nothing to do with the engine or transmission.

Window Winding Regulators

The E90 period was plagued with damaged or faulty window regulators, which caused problems like jammed or out-of-track windows.

Disintegrating Interior

A common issue with early E90s was the peeling of the inside plastics at the door handles, the wheel, and the center console. Light-colored automobile interiors were more likely to have this problem.

Sensing Device for Occupancy of a Passenger Seat

If a passenger seat sensor fails, the airbag warning indicator will light up in the instrument cluster. This problem can only be solved indefinitely by replacing the sensors.

Conclusion

The BMW E90 platform is generally reliable but has a few common mechanical problems you should know if you consider purchasing a used E90. Oil leaks in the oil pan, filter housing, and valve cover gaskets are widespread. Ignition coils often fail, leading to misfires, and the VANOS solenoid can malfunction.

Fuel injector problems can cause over-fueling, and carbon buildup can reduce efficiency. High-pressure fuel pumps (HPFP) can fail, and diesel engines have issues with emissions management systems, including the DEF/SCR tank, the diesel particulate filter, and the EGR system.

Lastly, some E90s have had issues with their electronics, including battery drains and faulty modules.

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Drawing from extensive expertise in the used car parts industry, Craig Sandeman has established himself as a trusted authority in automotive repair. He possesses a deep knowledge of the challenges encountered by individuals seeking reliable car parts, making him a highly sought-after expert in this field.

Disclaimer

Potential issues, causes, and solutions have been identified in the above article based on the experiences of car owners and repairers, as well as web materials such as forum blogs and technical support bulletins. This data is supplied exclusively for the purpose of reference. Only appropriately qualified persons should perform repairs and/or changes on your vehicles.

While it’s important to keep in mind, it’s also important to note that the amount of times anything is mentioned here should not be seen as a sign of its reliability or frequency. Various owners, driving in different ways, and caring for their vehicles in distinct ways will cause two identical vehicles to perform differently.

As previously said, this material is supplied primarily for reference reasons; nonetheless, we hope that by doing so, we will be able to supply you with essential knowledge that will allow you to make informed decisions whenever you encounter any of the aforementioned setbacks.

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