BMW 4 Series2021

Known issues

• DPF regeneration issues causing limp mode and excessive fuel consumption on short urban journeys
• AdBlue heater failure leading to warning lights and potential limp mode; heater element costs €600–€900
• Diesel particulate filter and NOx sensor degradation requiring expensive replacement (€1,200–€2,000)
• Gearbox shudder on low-speed manoeuvres, particularly with the 8-speed automatic; BMW software updates sometimes required
• Fuel injector carbon deposits on direct-injection engines reducing efficiency and causing rough idle after 60,000 km
• Cooling system issues with water pump failure around 80,000–100,000 km; not covered under warranty after 3 years

Good for

• Excellent fuel economy and low CO2 emissions on mixed driving (40–50 mpg typical real-world)
• Strong low-end torque and responsive diesel engine feel for motorway cruising
• Well-appointed interior with modern technology and comfortable driving position
• Good handling dynamics and premium build quality typical of BMW 4 Series