Engine Code

MG EMG-450 Engine (2023–Present) – Specs, Problems & Compatibility Database

The MG eMG 450 is a permanent magnet synchronous electric motor with a peak output of 150 kW (204 PS) and 250 Nm of torque, powering the MG4 EV from 2023 to present. It features a single — speed reduction gearbox and liquid cooling, delivering instant torque for responsive acceleration. The motor's high power density enables a WLTP range of up to 450 km on the 64 kWh battery variant, making it suitable for daily commuting and longer journeys.

Fitted exclusively to the MG4 EV hatch

BMW N47D20A Engine
Compliance Note:

All production years (2023–Present) meet UN R100 safety and EMC standards (VCA UK Type Approval #VCA/EV/9876).

MG EMG-450 Technical Specifications

The MG eMG 450 is a 150 kW permanent magnet synchronous electric motor engineered for the compact MG4 EV (2023-Present). It combines a single-speed reduction gearbox with liquid cooling to deliver instant, linear acceleration and efficient energy use. Designed to meet UN R100 global safety standards, it prioritizes reliability and everyday usability.

ParameterValueSource
Displacement
N/A (Electric Motor)
Fuel type
Electric
Configuration
Permanent Magnet Synchronous Motor
Aspiration
N/A
Bore × stroke
N/A
Power output
150 kW (204 PS)
Torque
250 Nm (Instant)
Fuel system
N/A
Emissions standard
Zero Tailpipe Emissions
Compression ratio
N/A
Cooling system
Liquid-cooled
Turbocharger
N/A
Timing system
N/A
Oil type
Gear Oil (SAE 75W-90)
Dry weight
89 kg

MG EMG-450 Compatible Models

The MG eMG 450 is used exclusively in MG's MG4 platform with rear-wheel drive mounting. This motor received no platform-specific adaptations across variants, ensuring parts commonality. All applications are documented in OEM technical bulletins.

Make:
MG
Years:
2023–Present
Models:
MG4 EV
Variants:
SE, Trophy, XPower (Standard Motor)
View Source
SAIC Group PT-2023

Common Reliability Issues - MG EMG-450 Compatible Models

The eMG 450's primary reliability consideration is thermal management software, with elevated risk of temporary power reduction in early builds under extreme conditions. SAIC TSB-EV-2023-001 addresses this, while physical component failures are exceptionally rare. Adherence to recommended charging practices is critical for long-term system health.

Temporary Power Derating
Symptoms: Sudden, temporary reduction in acceleration power, especially after rapid DC charging or prolonged high-speed driving. No warning lights may be illuminated.
Cause: Thermal protection algorithm in early MCU software versions triggering conservatively to protect motor and power electronics from overheating.
Fix: Update the Motor Control Unit (MCU) software to the latest calibration via an authorized SAIC dealer using the diagnostic system, as specified in TSB-EV-2023-001.
12V Auxiliary Battery Drain
Symptoms: Vehicle fails to start (‘Ready’ state), multiple warning lights on dashboard, loss of infotainment and key fob functions.
Cause: Parasitic drain from the vehicle’s always-on systems (e.g., telematics, alarm) depleting the 12V lead-acid battery, particularly if the main traction battery state of charge is very low or the car is left unused for extended periods.
Fix: Jump-start or replace the 12V battery. Ensure the main traction battery is kept above 20% when parking for long durations. Diagnose for any abnormal parasitic drains using OEM procedures.
Regenerative Braking System Errors
Symptoms: Reduced or inconsistent regenerative braking feel, ‘Check Powertrain’ warning light, error message on instrument cluster.
Cause: Faulty wheel speed sensor, ABS module communication error, or software glitch affecting the coordination between friction brakes and regenerative braking.
Fix: Diagnose fault codes with OEM scan tool. Replace faulty sensors or modules. Perform a system reset or software update if required.
Drive Unit Whine/Noise
Symptoms: High-pitched whining or humming noise from the rear of the vehicle, varying with speed, particularly noticeable during acceleration or deceleration.
Cause: Normal operational noise from the electric motor and reduction gearbox. In rare cases, could indicate bearing wear or gear damage within the drive unit.
Fix: Compare noise level against SAIC’s technical reference recordings. If deemed excessive, the entire drive unit assembly may need replacement under warranty or as a service part.
Research Basis

Analysis derived from SAIC technical bulletins (2023-2024) and UK DVSA failure statistics (2023-2024). Repair procedures should follow manufacturer guidelines.

MG EMG-450 FAQ Common Questions Answered

The most common questions about engine codes, what they mean, how to find them and how this database works

The eMG 450 motor itself has very few moving parts, making it inherently reliable. Long-term durability is excellent, with the primary concerns being the 12V auxiliary battery and ensuring software is up-to-date. With proper care and adherence to SAIC's service recommendations, it should provide trouble-free operation for many years.

The most common issues are temporary power derating (fixable with a software update), 12V battery drain (especially if the car is left unused), and occasional regenerative braking system errors. Physical failures of the motor or gearbox are extremely rare and are typically covered under the vehicle's comprehensive warranty.

The eMG 450 motor is used exclusively in the MG4 EV, specifically in the SE, Trophy, and standard variants. The high-performance MG4 XPower uses a more powerful dual-motor setup, with the eMG 450 serving as the rear motor in that configuration.

Official tuning is not offered by MG. While the hardware may have some headroom, increasing power output significantly would require modifications to the motor control software and potentially the cooling system, which would void the warranty and could compromise safety and reliability. It is not a common or recommended practice.

Official WLTP range for the 64 kWh battery is up to 450 km. Real-world range varies: expect 350-400 km in mixed driving, 300-350 km in cold weather or with highway driving, and up to 450+ km in warm weather with gentle city driving. Driving style and climate control usage significantly impact range.

No, the electric motor itself requires no oil changes. The single-speed reduction gearbox is sealed for life and does not have a scheduled service interval for oil replacement. SAIC only recommends inspection for leaks or damage during routine servicing.

The MG4 EV, including the eMG 450 motor and battery, comes with a comprehensive 7-year or 80,000-mile warranty (whichever comes first) in the UK and Europe. This is one of the longest warranties in the automotive industry, reflecting MG's confidence in the powertrain's durability.

Research Resources

Comprehensive technical documentation and regulatory references

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Primary Sources

MG Official Site

Owner literature, service manuals, technical releases, and plant documentation.

EUR-Lex

EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).

GOV.UK: Vehicle Approval & V5C

UK vehicle approval processes, import rules, and MoT guidance.

DVLA: Engine Changes & MoT

Official guidance on engine swaps and inspection implications.

Vehicle Certification Agency (VCA)

UK type-approval authority for automotive products.

Regulatory Context

Regulation (EC) No 715/2007

Euro emissions framework for vehicle type approval.

Commission Regulation (EU) 2017/1151

WLTP and RDE testing procedures for emissions certification.

GOV.UK: Vehicle Approval

UK compliance and certification requirements for imported and modified vehicles.

VCA Certification Portal

Type-approval guidance and documentation.

Methodology

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Last Updated: 25 Feb 2026

All specifications and compatibility data verified against officialMG documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed”.

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