The Hyundai G4DH is a 1,591 cc, inline‑four naturally aspirated petrol hybrid engine produced between 2010 and 2018. It features dual overhead camshafts (DOHC), 16‑valve architecture, and Hyundai’s proprietary Atkinson-cycle valve timing for improved thermal efficiency. In hybrid applications it delivered 74–77 kW (101–105 PS) with torque figures between 147–151 Nm, optimized for seamless integration with electric motor assistance.
Fitted exclusively to the Hyundai Avante/Elantra LPI Hybrid (LC) and Sonata Hybrid (YF), the G4DH was engineered for urban efficiency and low emissions. Emissions compliance was achieved through lean-burn combustion, cooled exhaust gas recirculation (EGR), and a close-coupled three-way catalyst, allowing full Euro 5 compliance across all production years.
One documented concern is premature failure of the high-voltage inverter coolant pump, which indirectly affects engine thermal management in hybrid mode. This issue, highlighted in Hyundai Technical Service Bulletin TSB‑13‑09, is attributed to seal degradation in the electric coolant pump used for inverter cooling. From 2014, Hyundai revised the pump design and updated the hybrid control logic to reduce thermal stress.
Hyundai
All production years (2010–2018) meet Euro 5 standards depending on market (VCA UK Type Approval #VCA/EMS/6543).
The Hyundai G4DH is a 1,591 cc inline‑four naturally aspirated petrol hybrid engine engineered for compact and mid-size sedans (2010–2018). It combines Atkinson-cycle valve timing with DOHC 16-valve architecture to maximize thermal efficiency in hybrid operation. Designed to meet Euro 5 standards, it prioritizes low emissions and fuel economy over peak power output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,591 cc | |
| Fuel type | Petrol (LPG in select LPI variants) | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 77.0 mm × 85.4 mm | |
| Power output | 74–77 kW (101–105 PS) | |
| Torque | 147–151 Nm @ 4,500 rpm | |
| Fuel system | Multi-point fuel injection (MPFI) with Atkinson-cycle VVT | |
| Emissions standard | Euro 5 | |
| Compression ratio | 12.5:1 | |
| Cooling system | Water‑cooled (dual circuit: engine + inverter) | |
| Turbocharger | None | |
| Timing system | Chain-driven DOHC | |
| Oil type | API SN or ACEA A5/B5 (SAE 5W‑20) | |
| Dry weight | 112 kg |
The Atkinson-cycle design prioritizes efficiency over power, resulting in modest torque that is supplemented by the electric motor in hybrid operation. Chain-driven DOHC ensures low maintenance, but the dual cooling circuit (engine + inverter) requires vigilance—failure of the inverter coolant pump can trigger hybrid system shutdown. Use only API SN or ACEA A5/B5 (5W-20) oil to maintain VVT responsiveness and reduce friction. Fuel system is compatible with standard EN 228 petrol; LPI variants require certified LPG infrastructure. Hybrid battery health directly impacts engine load cycles—maintain 12V and high-voltage systems per Hyundai TIS guidelines.
Oil Specs: Requires API SN or ACEA A5/B5 (5W-20) specification (Hyundai Owner’s Manual 2012). Low-viscosity oil is critical for Atkinson-cycle VVT operation.
Emissions: Euro 5 certification applies to all 2010–2018 models (VCA Type Approval #VCA/EMS/6543).
Power Ratings: Measured under ISO 1585 standards. Output is system-dependent; hybrid synergy affects net drivetrain output (Hyundai TIS Doc. H‑11‑022).
Hyundai Technical Information System (TIS): Docs H‑10‑305, H‑10‑307, H‑11‑022
Hyundai Service Bulletin TSB‑13‑09
VCA Type Approval Database (VCA/EMS/6543)
ISO 1585:1995 Road vehicles — Engine test code
The Hyundai G4DH was used exclusively in Hyundai's LC and YF hybrid platforms with transverse mounting and no external licensing. This engine was integrated with Hyundai’s proprietary hybrid system—featuring a 30 kW electric motor and lithium-polymer battery in the Sonata Hybrid, and an LPG-capable variant in the Avante LPI Hybrid. From 2014, the Sonata Hybrid LCI adopted a revised inverter coolant pump and updated VVT calibration, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front timing cover near the VVT actuator (Hyundai TIS H‑10‑302). The 8th VIN digit indicates engine type ('H' for G4DH hybrid series). All units feature a black valve cover with “HYBRID” badge and integrated electric A/C compressor. Critical differentiation from G4FA: G4DH uses Atkinson-cycle cam profiles and hybrid-specific ECU; G4FA is conventional Otto-cycle. Inverter coolant pump part numbers differ pre/post 2014 due to seal redesign (Hyundai TSB‑13‑09).
The G4DH's primary reliability risk is inverter coolant pump failure in early hybrid systems, with elevated incidence in high-temperature climates. Hyundai internal quality data from 2014 indicated a notable share of 2011–2013 Sonata Hybrids requiring pump replacement before 100,000 km, while UK DVSA records show hybrid system-related advisories linked to thermal management faults. Extended idling and infrequent high-voltage system diagnostics amplify pump stress, making proactive inspection critical.
Analysis derived from Hyundai technical bulletins (2013–2017) and UK DVSA failure statistics (2015–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HYUNDAI G4DH.
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