BMW B46 2.0 Turbo: Specs, Engine Codes, ECUs & Maintenance
BMW · Engine information · U.S. & Canada
B46
2.0 turbo · Modular design, emissions-focused detail
The B46 combines a strong midrange with BMW’s modular four-cylinder design. Its emissions equipment and technical updates matter just as much as the 30i badge when identifying the engine and its controller.
Gold Pony · CC BY · cropped video still
Architecture
- Original code
- B46B20O0 · longitudinal
- Updated code
- B46B20O1 · B46TU
- Bore × stroke
- 82.0 × 94.6 mm
- Block / head
- Aluminium / aluminium
- Compression
- 11.0:1 original · 10.2:1 TU
- Induction
- Single twin-scroll turbo
Fuel & control
- Injection
- Direct · solenoid
- Rail pressure
- 200 bar original · 350 bar TU
- Valve control
- Double VANOS + Valvetronic
- Charge cooling
- Indirect, liquid-cooled
- TU features
- Revised chain drive and split cooling
- Emissions
- Application-specific SULEV equipment
Engine controllers · Bosch MG1CS003 / MG1CS201
BMW’s DME designation and the Bosch hardware number describe different sides of the same controller. Original longitudinal engines use MG1CS003; the technical update moves to MG1CS201. Software also distinguishes emissions certification, transmission and vehicle installation.
| Controller | Applications & timing | Technical distinction |
|---|---|---|
| MG1CS003 · DME 8.4.1 | Original longitudinal B46 in F-series, including 2017–2018 F30 330i | MPC5777 processor; F-series software and vehicle-network integration. |
| MG1CS003 · DME 8.4.0 | Original longitudinal B46 in G-series applications | Same Bosch hardware family; different BMW integration and calibration. |
| MG1CS201 · DME 8.4.T0 | B46TU, including G20 330i and G29 Z4 from 2019 | TC298 processor; supports the updated 350-bar fuel system and revised thermal control. |
These rows cover longitudinal B46 engines. Transverse B46A20 installations can use MEVD17.2.3 or MG1CS201/DME 8.4.T1. Match the complete engine and DME identification before selecting software.
Selected U.S. & Canadian vehicles
| Model | Chassis | Model years | Engine / factory output |
|---|---|---|---|
| 330i | F30 / F31 | 2017–2018 | B46B20O0 · 248 hp / 258 lb-ft |
| 430i | F32 / F33 / F36 | 2017–2020 | B46-equipped builds · 248 hp / 258 lb-ft |
| 530i / X3 30i | G30 / G01 | 2017–2020 / 2018–2021 | Original B46-equipped builds · 248 hp / 258 lb-ft |
| 330i / Z4 sDrive30i | G20 / G29 | 2019–2022 | B46TU-equipped builds · 255 hp / 295 lb-ft |
B46 and B48 availability differs by market and emissions certification. Model badges alone do not identify the engine; later revisions are outside this table.
Common issues & key risks
Oil-filter-housing leaks. The housing and its seals can lose coolant or oil. Pressure-test low coolant levels and inspect the housing beneath the intake before replacing unrelated cooling parts.
Coolant vent line. The cylinder-head quick connector can break on affected earlier applications. BMW issued a service action for specified 2015–2018 builds; check the VIN and repair history.
Pump & heat-management module. Pump seals can leak, while the coolant-control module can leak or stick. Temperature warnings and coolant-control faults need diagnosis before sustained load.
EVAP purge valve. A faulty tank-vent valve can trigger an engine warning and uneven running. BMW lists component coverage for eligible applications; confirm the diagnosis and VIN eligibility.
Misfires & ventilation. Check plugs and coils for load-related misfires. Whistling or abnormal oil use calls for a crankcase-pressure test, rather than assuming turbo failure.
Keep it consistent: Follow the oil approval and service schedule for the exact build. Short trips and sustained high load justify reviewing service frequency with your technician.
References
| Topic | Source |
|---|---|
| Technical update | BMW B46TU/B48TU training |
| Filter-housing failure | FCP Euro · housing failure modes |
| Cylinder-head vent line | BMW SI B17 01 21 |
| Cooling-system repairs | FCP Euro · shared B48/B58 cooling components |
| Purge-valve coverage | BMW SI B01 02 24 · reproduced bulletin |
| Photograph | Gold Pony · 2020 BMW 330i Review | This or 2020 Audi A4? · CC BY. Cropped video still at 1:19. |
Model years refer to selected U.S. and Canadian applications. Equipment and software vary by build. Use current BMW service information for diagnosis and repair.
