2021 BMW M340i B58B30M0/B58B30O1 (G20)
G20 / Sedan / Global (with variations in North America, Europe, Asia)
B58B30M0B58B30O1Exact year/trim recordSilver
Engine identity
Oils and fluids
Service and parts data
Common and chronic problems
- Carbon buildup on intake valves (direct injection engines)
- Turbocharger wastegate rattle in some early production units
- Transient electrical gremlins related to infotainment system
First checks
- Check oil condition and level regularly due to turbocharging
- Monitor for turbo lag or unusual noise
- Inspect cooling system hoses and radiator for leaks
Before replacing parts
- Save fault codes and freeze-frame data before clearing anything.
- Check engine oil, coolant and transmission fluid using the correct temperature and service procedure.
- Verify power, ground, connectors, hoses, leaks and live data before replacing expensive parts.
Important notes
- 2021 M340i uses BMW’s B58 engine, recognized for smooth power and efficiency.
- Market-specific power output adjustments arise from emissions compliance.
- Oil and fluid capacities can vary marginally with transmission choice and market regulations.