The BMW B46 A20 B is a 1,998 cc, inline-four turbocharged petrol engine produced from 2020 to 2024. Part of BMW's modular B-series engine family, it features TwinPower Turbo technology, high-precision direct fuel injection, and Valvetronic variable valve control. Delivering 135 kW (184 PS) and 300 Nm of torque from 1,350 rpm, this engine is tuned for responsive urban driving and efficient highway cruising.
Installed in mid-range BMW models such as the G20 3 Series (320i), G29 Z4, and G01 X3 (xDrive20i), the B46 A20 B emphasizes a balance between performance and fuel efficiency while maintaining BMW's hallmark driving dynamics. It meets stringent Euro 6d-ISC-FCM emissions standards thanks to its integrated gasoline particulate filter (GPF), optimized combustion chamber design, and intelligent thermal management system.
In 2022, BMW issued Technical Service Bulletin 11 54 22 addressing early reports of high-pressure fuel pump (HPFP) noise and rail pressure fluctuations. The update included revised HPFP control logic and updated injector calibration to improve fuel delivery stability. This change reduced instances of cold-start hesitation and improved long-term injector longevity, particularly in stop-start driving conditions.
All production years 2020–2024 meet Euro 6d-ISC-FCM standards (VCA UK Type Approval #VCA/EMS/8901).
The BMW B46 A20 B is a 1,998 cc inline-four turbocharged petrol engine engineered for mid-size and sports models (2020–2024). It combines TwinPower Turbo with direct injection and Valvetronic to deliver strong low-end torque and smooth power delivery. Designed to meet Euro 6d-ISC-FCM, it balances everyday usability with emissions compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,998 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Single-scroll turbocharged | |
| Bore × stroke | 82.0 mm × 94.6 mm | |
| Power output | 135 kW (184 PS) @ 5,000–6,500 rpm | |
| Torque | 300 Nm @ 1,350–4,000 rpm | |
| Fuel system | High-pressure direct injection (up to 350 bar) | |
| Emissions standard | Euro 6d-ISC-FCM | |
| Compression ratio | 11.0:1 | |
| Cooling system | Water-cooled, electric thermostat control | |
| Turbocharger | Single-scroll turbo (BorgWarner) | |
| Timing system | Chain-driven (double-row primary, single-row secondary) | |
| Oil type | BMW Longlife-17 (LL-17 FE+) 0W-20 | |
| Dry weight | 142 kg |
The single-scroll turbo provides adequate low-end response for daily driving but benefits from regular highway runs to maintain charge air cooler and intake port cleanliness. Strict adherence to 15,000 km oil change intervals using BMW Longlife-17 0W-20 is essential for Valvetronic actuator and timing chain longevity. The gasoline particulate filter (GPF) requires periodic regeneration; frequent short trips may lead to clogging. Cold starts should avoid immediate high RPM until oil pressure stabilizes. The high-pressure fuel pump is sensitive to fuel quality; use of premium unleaded (RON 95 minimum) is recommended. Post-2022 models feature revised ECU mapping to improve fuel delivery stability; pre-2022 units should follow BMW SIB 11 54 22 for calibration updates.
Oil Specs: Requires BMW Longlife-17 (LL-17 FE+) 0W-20 specification (BMW SIB 11 54 22). Supersedes LL-01 and LL-04 for petrol engines.
Emissions: Euro 6d-ISC-FCM certification applies to all models (2020–2024) (VCA Type Approval #VCA/EMS/8901).
Power Ratings: Measured under SAE J1349 standards. Full output requires RON 95 fuel (BMW TIS Doc. A30005).
BMW Technical Information System (TIS): Docs A30005, SIB 11 54 22
VCA Type Approval Database (VCA/EMS/8901)
SAE International: J1349 Engine Power Certification Standards
The BMW B46 A20 B was used across BMW's G20/G29/G01 platforms with longitudinal mounting. This engine received platform-specific adaptations-intake tuning in the G20 3 Series and transmission calibration in the G29 Z4-and from 2022 received updated high-pressure fuel pump control logic to improve fuel delivery stability, creating minor service part and software differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block, near the oil filter housing (BMW TIS A30020). The 7th VIN digit indicates engine family ('B' for B-series). Pre-2022 models have a silver high-pressure fuel pump housing; post-2022 units use updated ECU calibration (ZP22.03.10 or later) to improve fuel delivery stability. Critical differentiation from B48: B46 A20 B is a detuned 2.0L variant with lower power output and different turbo calibration; B48 is used in higher-output models. Service parts require production date verification—fuel pumps and injectors for pre-2022 models may benefit from updated calibration per BMW SIB 11 54 22.
The B46 A20 B's primary reliability concern is high-pressure fuel pump instability in early builds, particularly in vehicles used primarily for short urban trips. Internal BMW field reports from 2023 indicated a rise in cold-start hesitation complaints below 80,000 km in pre-update units, while UK DVSA data shows low rates of emissions failures due to effective GPF management. Frequent cold starts and low-RPM operation increase fuel system stress, making ECU updates and maintenance critical for long-term performance.
Analysis derived from BMW technical bulletins (2020–2024) and UK DVSA failure statistics (2021–2025). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW B46A20B.
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