2018 model year · 450+ owner reports · Updated April 2026
According to Au7o's analysis of 450+ owner reports, the 2018 BMW 4 Series has 7 documented known issues. No issues are rated critical, indicating generally reliable ownership. The most commonly reported issue is B58 Charge Pipe Pop-Off Under Boost with 250 owner reports. Across all issues, repair costs range from $150 to $3,500. DIY maintenance guides at au7o.io.
On the 2017-2025 BMW 4 Series B58, the plastic charge pipe (intercooler to throttle body) on B58-powered 440i and M440i models can pop off or crack under high boost pressure, especially in warm weather or during spirited driving. The OEM plastic pipe uses a pressed-on connector that weakens over heat cycles. When the pipe disconnects, the engine immediately loses boost pressure and enters limp mode with significant power loss.
Replace the OEM plastic charge pipe with an upgraded aluminum aftermarket unit. These use proper clamp-style connections that won't pop off under pressure. If replacing with OEM, use the latest revision part number. Check the intercooler boots and couplings for damage from the pressure release event.
Parts and tips from 250+ owners who fixed this issue
On the 2014-2020 BMW 4 Series, the valve cover gasket on N20 (428i) and N55 (435i) engines develops leaks typically between 60,000-90,000 miles. The integrated PCV valve within the valve cover can also fail, causing excessive crankcase pressure, oil consumption, and rough running. Oil seepage from the valve cover can contaminate spark plug wells and cause misfires.
Replace the entire valve cover assembly as the gasket and PCV are integrated into the plastic cover on both N20 and N55 engines. Clean spark plug wells of any oil contamination and replace spark plugs if oil-fouled. Use a torque wrench to properly seat the new cover — over-tightening cracks the plastic housing.
Parts and tips from 200+ owners who fixed this issue
On the 2014-2020 BMW 4 Series, bMW uses a plastic charge pipe (boost pipe) to route pressurized air from the turbocharger to the engine intake. The plastic becomes brittle over time due to heat cycles and boost pressure. The pipe commonly cracks or the connection points fail, causing a sudden loss of boost pressure. This results in immediate power loss and limp mode. The failure typically occurs between 50,000-80,000 miles. All turbocharged F-chassis BMWs (N20, N55 engines) are affected. Many owners upgrade to aluminum charge pipes to prevent recurrence.
Replace charge pipe. OEM replacement is plastic and will fail again. Aftermarket aluminum charge pipe is highly recommended for permanent fix. Popular brands: ARM Motorsports, Burger Motorsport (BMS), VRSF. Installation is straightforward DIY for experienced mechanics. Also inspect intercooler boots and clamps for cracks while charge pipe is removed.
Parts and tips from 0+ owners who fixed this issue
On the 2014-2018 BMW 4 Series N55, the N55 engine uses an electric auxiliary water pump (in addition to the mechanical pump) that commonly fails between 60,000-100,000 miles. The electric pump circulates coolant when the engine is off to prevent heat soak and during cold starts. Pump bearing wear and seal failure lead to coolant leaks and pump motor burnout. Symptoms include coolant loss, overheating warnings, and heater malfunction. This is a wear item that will eventually fail on all N55 engines (also affects 335i, 535i, X5 35i, X6 35i).
Replace electric water pump. Also inspect main mechanical water pump and thermostat for leaks/failure while repair is being performed. Replace coolant with BMW-approved coolant (blue or newer orange). Bleed cooling system properly after replacement to avoid air pockets. Some mechanics recommend replacing both pumps together since labor overlaps.
Parts and tips from 0+ owners who fixed this issue
On the 2014-2018 BMW 4 Series, the N55 3.0L turbocharged inline-6 engine in 435i and early 440i models experiences VANOS (Variable Valve Timing) solenoid failures. These solenoids control oil flow to the VANOS system for variable valve timing. Internal wear causes them to stick or fail, leading to rough running, power loss, and check engine lights. The intake VANOS solenoid (cylinder head front) fails more frequently than the exhaust solenoid. Oil contamination and sludge accelerate failure. This is a common issue shared with N55-powered 335i, 535i, and X5 35i models.
Replace failed VANOS solenoid(s). Both intake and exhaust solenoids should be inspected. Clean VANOS system if contaminated with sludge. Use high-quality full synthetic oil (BMW LL-01 spec) and maintain 7,500-mile oil change intervals to prevent premature failure. Some shops recommend replacing both solenoids preventively.
Parts and tips from 0+ owners who fixed this issue
On the 2014-2020 BMW 4 Series, direct injection fuel injectors on N20 and N55 engines commonly fail between 60,000-100,000 miles due to carbon buildup and high-pressure operation. Injector internal seals wear out, causing fuel leaks or inconsistent spray patterns. Failed injectors cause rough running, misfires, and poor fuel economy. Carbon deposits on intake valves (common on direct injection engines) worsen the problem. BMW uses Bosch high-pressure injectors that operate at 2,000+ PSI. When one injector fails, others often follow soon after.
Replace failed injector(s). BMW recommends replacing all injectors together to prevent repeat repairs. Perform walnut blast carbon cleaning on intake valves while injectors are out (labor overlap saves money). Use Top Tier gasoline with detergent additives to minimize carbon buildup. Some owners add Liqui Moly Valve Clean to fuel tank every 5,000 miles preventively.
Parts and tips from 0+ owners who fixed this issue
On the 2014-2020 BMW 4 Series, the F33 4 Series convertible uses a complex hydraulic folding hardtop system that commonly experiences pump and motor failures. The hydraulic pump motor burns out from overheating or seal leaks cause hydraulic fluid loss. Top becomes stuck in partially open/closed position. Microswitch sensors that detect top position also fail frequently, preventing top operation even when hydraulics work. Exposure to weather and infrequent operation accelerate failures. This affects all F33 convertibles and is similar to issues in E93 3 Series convertibles.
Diagnose specific failure point - pump motor, hydraulic lines, microswitches, or latch mechanisms. Hydraulic pump motor replacement is most common repair. Check hydraulic fluid level and refill if low. Inspect all microswitches and sensors for proper operation. Regular top cycling (once per month minimum) prevents seals from drying out. Store with top up to reduce strain on hydraulics.
Parts and tips from 0+ owners who fixed this issue
POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)
BMW of North America, LLC (BMW) is recalling certain 2023 Toyota GR Supra, 3 Series Sedan (330i xDrive, M340i xDrive, M3), 5 Series Sedan (530i, 530i xDrive, M5), 4 Series Gran Coupe (430i, 430i xDrive), 4 Series Coupe (430i, 430i xDrive, M440i xDrive), 4 Series Convertible (430i, 430i xDrive, M440i xDrive), 8 Series Coupe (840i, M850i xDrive, M8), 8 Series Convertible (840i, M850i xDrive, M8), 8 Series Gran Coupe (850i xDrive, M8), X3 SAV (X3 xDrive30i, X3M), X4 SAV (X4 xDrive30i), X5 SAV (X5 xDrive40i, X5 M50i, X5M), X6 SAV (X6 xDrive40i, X6 M50i, X6M), and Z4 sDrive30i, Z4 M40i vehicles. The weld seam of the integrated transmission control unit's cover may not have been manufactured properly, which could allow automatic transmission oil to leak into the transmission control unit.
Enter your VIN at NHTSA.gov to check recalls specific to your vehicle.
Don't see your problem? Describe your symptoms to get a diagnosis, or get a full repair guide.
According to Au7o's analysis of 450+ owner reports, the 2018-2018 BMW 4 Series has 7 documented issues. The most frequently reported are: B58 Charge Pipe Pop-Off Under Boost, Valve Cover Gasket Leak and PCV Failure, Turbo Charge Pipe Failure - 428i/435i/440i F32/F33/F36. None are rated critical, but regular maintenance is recommended.
The 2018-2018 BMW 4 Series has 7 known issues documented across 450+ owner reports. No issues are rated critical, suggesting generally good reliability. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
Repair costs for known BMW 4 Series issues range from $150 to $3,500, depending on the specific problem and whether you choose DIY or professional repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
The plastic charge pipe (intercooler to throttle body) on B58-powered 440i and M440i models can pop off or crack under high boost pressure, especially in warm weather or during spirited driving. The OEM plastic pipe uses a pressed-on connector that weakens over heat cycles. When… Repairs typically run $200-$500. Severity: medium.
The valve cover gasket on N20 (428i) and N55 (435i) engines develops leaks typically between 60,000-90,000 miles. The integrated PCV valve within the valve cover can also fail, causing excessive crankcase pressure, oil consumption, and rough running. Oil seepage from the valve co… Repairs typically run $500-$1,200. Severity: medium.
BMW uses a plastic charge pipe (boost pipe) to route pressurized air from the turbocharger to the engine intake. The plastic becomes brittle over time due to heat cycles and boost pressure. The pipe commonly cracks or the connection points fail, causing a sudden loss of boost pre… Repairs typically run $150-$600. Severity: medium.
The N55 engine uses an electric auxiliary water pump (in addition to the mechanical pump) that commonly fails between 60,000-100,000 miles. The electric pump circulates coolant when the engine is off to prevent heat soak and during cold starts. Pump bearing wear and seal failure… Repairs typically run $400-$900. Severity: medium.
The N55 3.0L turbocharged inline-6 engine in 435i and early 440i models experiences VANOS (Variable Valve Timing) solenoid failures. These solenoids control oil flow to the VANOS system for variable valve timing. Internal wear causes them to stick or fail, leading to rough runnin… Repairs typically run $250-$800. Severity: medium.
The F33 4 Series convertible uses a complex hydraulic folding hardtop system that commonly experiences pump and motor failures. The hydraulic pump motor burns out from overheating or seal leaks cause hydraulic fluid loss. Top becomes stuck in partially open/closed position. Micro… Repairs typically run $1,200-$3,500. Severity: medium.
Direct injection fuel injectors on N20 and N55 engines commonly fail between 60,000-100,000 miles due to carbon buildup and high-pressure operation. Injector internal seals wear out, causing fuel leaks or inconsistent spray patterns. Failed injectors cause rough running, misfires… Repairs typically run $800-$2,500. Severity: medium.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.
