BMW M240i F22

The B58's cooling system is its most common weak point, continuing BMW's tradition of heat-sensitive plastic coolant components. The coolant vent hose running from the oil filter housing module to the expansion tank becomes brittle after 60,000-80,000 km from heat cycles and can crack, causing a slow coolant loss. The expansion tank itself is made of thermoplastic that degrades under repeated heat cycling and can develop hairline cracks. The electric water pump typically lasts 80,000-120,000 km before internal seals begin to weep. A vent hose replacement alone runs €200-400, but if the water pump and thermostat need replacement together, the bill reaches €800-1,500 at a BMW dealer due to labor-intensive access. Proactively replacing the vent hose at 80,000 km and monitoring coolant levels regularly can prevent escalation.

The oil filter housing gasket is a common leak point on virtually all modern BMWs, and the B58 is no exception. The rubber gasket becomes brittle from heat cycles after 60,000-100,000 km, allowing oil to seep past the housing. If left unaddressed, oil can drip onto the serpentine belt or contaminate the cooling system through the integrated heat exchanger. The repair is straightforward: €300-500 at an independent specialist, rising to €500-700 at a BMW dealer. The gasket itself costs €20-40, with the bulk of the expense being labor (2-3 hours). Often combined with valve cover gasket replacement to save on labor overlap.

The factory-fitted plastic charge pipe is a known weak point on B58-equipped BMWs. Under sustained high boost, the pipe can crack or blow off entirely, triggering a P0299 underboost code and immediate limp mode. This is especially common on cars that are driven hard, have been tuned, or operate in hot climates. Stock M240i cars driven gently can run the OEM pipe for 80,000+ km without issue, but the failure mode is sudden and always at the worst moment. The recommended fix is an aftermarket aluminum charge pipe (€150-250 for the part, plus €50-150 for fitting). Many owners upgrade this preventatively. BMW does not acknowledge it as a design flaw.

The B58's Positive Crankcase Ventilation (PCV) system uses a rubber diaphragm built into the valve cover assembly. Over time, this diaphragm can rupture or tear, leading to excessive crankcase pressure, rough idle, increased oil consumption, and potentially oil leaks from overwhelmed seals. On the first-generation B58 (used in the F22 M240i), the PCV diaphragm can sometimes be replaced separately without removing the entire valve cover, costing €400-600. However, if the valve cover itself is damaged or the newer integrated design applies, the full valve cover assembly needs replacement at €800-1,200 including labor. BMW issued a technical service bulletin acknowledging this issue. Driving with a failed PCV system risks further engine damage.

Like all direct-injection engines, the B58 injects fuel directly into the combustion chamber, bypassing the intake valves. Over time, oil vapors from the crankcase ventilation system coat the intake valves with carbon deposits. This buildup is gradual and typically becomes noticeable between 80,000-120,000 km as rough idle, slight misfires, or reduced throttle response. The standard remedy is walnut shell blasting, which involves removing the intake manifold and mechanically cleaning the valves. In Western Europe, independent specialists charge €400-550 for this service, while BMW dealers typically charge €550-700. After cleaning, the engine runs noticeably smoother. Repeat intervals of 60,000-80,000 km are typical.

The B58's high-pressure fuel pump is significantly more robust than the units used in the older N54 and N55 engines, which were notorious for HPFP failures. On the B58, premature failure is uncommon, but gradual wear at very high mileage (100,000+ km) can occur, causing hard starting, rough running, or fuel pressure fault codes. Replacement costs €600-900 at an independent specialist and €900-1,200 at a BMW dealer. The part itself accounts for roughly half the cost. This is primarily a concern for high-mileage examples; most M240i owners will never encounter this issue within typical ownership periods.