The BMW B46 is a 2.0-liter turbocharged inline-four that serves as the SULEV (Super Ultra-Low Emissions Vehicle) and PZEV-certified variant of BMW's modular B48 engine. Introduced in 2016 and still in production, the B46 was engineered specifically for the strictest U.S. emissions markets, meaning it appears in cars sold in California and states that follow CARB regulations. Mechanically, it is nearly identical to the standard B48, differing chiefly in its emissions hardware and calibration.
What the B46 Is
The B46 belongs to BMW's modular engine family, which shares a common 500cc-per-cylinder architecture across three-, four-, and six-cylinder designs. That modular philosophy links it directly to the B38 three-cylinder and the B58 straight-six. The "SULEV" designation reflects additional emissions controls—more sophisticated catalyst systems and monitoring—that allow the engine to meet the toughest state standards while delivering the same driving character as the B48.
Engineering & Specs
- Configuration: 2.0L turbocharged inline-four
- Induction: Single twin-scroll turbocharger
- Output: 180–248 hp depending on tune
- Torque: 222–295 lb-ft
- Redline: 6,500 rpm
- Production: 2016–present
The twin-scroll turbo minimizes lag and builds boost early, giving the B46 a broad, flexible torque curve. Direct injection, Valvetronic variable valve lift, and Double-VANOS variable timing round out the package, all shared with the wider modular lineup.
Which BMWs Used It
Because the B46 is region-specific, it powers emissions-state versions of familiar models:
- 230i (2 Series)
- 330i (3 Series)
- 430i (4 Series)
- 530i (5 Series)
If you're unsure whether a given car carries a B46 or a standard B48, run its VIN through our VIN decoder to confirm the exact engine code.
Reliability & Ownership Notes
The B46 inherits the maturity and refinement of the modular B-series, which corrected many early N20 shortcomings. Owners should still follow disciplined maintenance: use the correct low-viscosity synthetic oil, keep service intervals short, and monitor the cooling system as the engine ages. Because SULEV emissions components can be more complex and occasionally more expensive to service, verify that a used example has a clean emissions and maintenance history.
For buyers, the practical takeaway is simple—a B46 drives identically to a B48 and shares the same performance ratings. The distinction matters mainly for parts sourcing and regional registration.
Legacy
The B46 represents BMW's commitment to meeting evolving emissions standards without compromising performance. As one branch of the modular family that also includes the B48 and B58, it remains a strong, dependable choice for enthusiasts in emissions-regulated states. Explore more engine profiles in the BMW DNA encyclopedia.