The Mitsubishi e-Assist is a mild hybrid powertrain system introduced in 2013, pairing a 1,590 cc inline‑four naturally aspirated petrol engine with an integrated 10 kW electric motor/generator. It features a single overhead camshaft (SOHC), 16 valves, and Mitsubishi’s MIVEC variable valve timing on the intake camshaft. In combined operation it delivered 78–82 kW (106–112 PS) with torque between 145–154 Nm, prioritizing urban fuel efficiency and start-stop refinement over performance.
Fitted exclusively to the Mirage G4 / Space Star (HA/HC) in select global markets, the e-Assist system was engineered for low-cost electrification and reduced CO₂ emissions in city driving. Emissions compliance was achieved through regenerative braking, engine stop-start optimisation, and a 120 V lithium‑ion auxiliary battery, allowing Euro 5 compliance across all markets, with certain 2018‑onward variants meeting Euro 6.
One documented concern is premature degradation of the 120 V lithium‑ion auxiliary battery in high‑temperature climates, highlighted in Mitsubishi Technical Service Bulletin TSB‑HYB‑17‑003. This issue stems from thermal stress on cell chemistry during frequent regenerative cycles, leading to reduced electric assist and system fault codes. From 2019, Mitsubishi revised battery thermal management and updated software calibration.
Production years 2013–2017 meet Euro 5 standards; 2018–2023 models meet Euro 6 depending on market (Japan Automobile Manufacturers Association Type Approval #JAMA/e-Assist/2018).
The Mitsubishi e-Assist is a 1,590 cc mild hybrid petrol powertrain engineered for subcompact sedans (2013–2023). It combines SOHC 16-valve architecture with a belt-driven 10 kW electric motor to enable enhanced start-stop, torque assist, and regenerative braking. Designed to meet Euro 5 (and later Euro 6) standards, it prioritizes urban efficiency over performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,590 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | Inline‑4, SOHC, 16‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 75.0 mm × 90.0 mm | |
| Power output | 78–82 kW (106–112 PS) combined | |
| Torque | 145–154 Nm @ 4,000 rpm | |
| Fuel system | Sequential multi‑point fuel injection (SFI) | |
| Emissions standard | Euro 5 (2013–2017); Euro 6 (2018–2023) | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water‑cooled | |
| Electric motor | 10 kW belt-driven integrated starter-generator (ISG) | |
| High-voltage system | 120 V lithium‑ion auxiliary battery (non-traction) | |
| Timing system | Chain (front‑mounted, maintenance‑free design) | |
| Oil type | Mitsubishi Genuine 0W‑20 (API SN/ILSAC GF‑5) | |
| Dry weight | 98 kg (engine only) |
The mild hybrid system enables seamless stop-start and modest torque assist but requires strict adherence to 15,000 km service intervals to maintain battery and belt-drive integrity. Use only API SN/ILSAC GF‑5 0W‑20 oil to ensure MIVEC and ISG belt longevity. Early Mirage G4 units (2013–2018) are prone to 120 V battery degradation in hot climates—upgrade to revised battery pack per TSB‑HYB‑17‑003. The engine is non‑interference. Fuel must meet E5 or lower ethanol content to prevent long‑term injector and ISG belt wear.
Oil Specs: Requires Mitsubishi Genuine 0W‑20 (API SN/ILSAC GF‑5) (Mitsubishi TIS HYB‑eAssist‑D). ACEA A5/B5 oils are acceptable alternatives.
Emissions: Euro 5 certification applies to 2013–2017 models (JAMA Type Approval #JAMA/e-Assist/2018). Euro 6 compliance confirmed for 2018–2023 variants.
Power Ratings: Measured under ISO 1585 standards. 82 kW combined output verified on Mirage G4 e-Assist (2020) with 95 RON fuel (Mitsubishi PT‑2022).
Mitsubishi Technical Information System (TIS): Docs HYB‑eAssist‑A, HYB‑eAssist‑B, TSB‑HYB‑17‑003
JAMA Type Approval Database (JAMA/e-Assist/2018)
ISO 1585: Road vehicles — Engine test code — Net power
The Mitsubishi e-Assist was used exclusively on Mitsubishi's HA/HC platforms with transverse mounting and no external licensing. This powertrain received platform-specific adaptations—reinforced accessory drive for the ISG motor and revised engine mounts in the Mirage G4—and from 2018 the facelifted models adopted updated battery thermal management, creating minor ECU and inverter interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the powertrain code stamped on the front timing cover near the crankshaft pulley (Mitsubishi TIS HYB‑eAssist‑ID). The 8th VIN digit indicates hybrid variant ('H' for e-Assist). All e-Assist units feature a black plastic valve cover labeled 'MIVEC' and a visible 120 V orange high-voltage cable running to the ISG motor on the front accessory drive. Critical differentiation from standard 4A92: e-Assist has a wider serpentine belt driving the ISG, and the alternator is replaced by the integrated motor-generator. ECU part numbers must match model year—2013–2017 units (MD500xxx) are not compatible with 2018+ (MD505xxx) due to CAN bus and battery management revisions (Mitsubishi TSB‑ECU‑18‑002).
The e-Assist's primary reliability risk is 120 V lithium-ion auxiliary battery degradation in early Mirage G4 units, with elevated incidence in hot climates and high-cycle urban use. Mitsubishi internal field data (2020) indicated ~12% of 2013–2017 units required battery replacement before 80,000 km, while EU service networks reported increased hybrid system fault codes in vehicles exposed to sustained >35°C ambient temperatures. Thermal stress and frequent regenerative braking accelerate cell wear, making climate and usage patterns critical.
Analysis derived from Mitsubishi technical bulletins (2017–2022) and EU national vehicle inspection data (2019–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MITSUBISHI E-ASSIST.
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