The Hyundai G6CT is a 2,656 cc, V6 naturally aspirated petrol engine produced between 2005 and 2010. It features a dual overhead camshaft (DOHC) layout with 24 valves and Hyundai’s Variable Intake System (VIS) for optimized airflow. In standard form it delivered 125–132 kW (170–180 PS) and torque figures between 245–255 Nm, providing smooth power delivery and refined highway cruising.
Fitted to models such as the Grandeur TG, Sonata NF, and Azera TG, including the 2.7 V6 GLS and Limited variants, the G6CT was engineered for mid-size sedan comfort, quiet operation, and responsive performance. Emissions compliance was achieved through sequential multi-point fuel injection, three‑way catalytic conversion, and precise ignition control, allowing conformity with Euro 4 standards across all production years.
One documented concern is premature wear of the hydraulic lash adjusters (HLAs), which can cause ticking noises and uneven valve operation. This issue, highlighted in Hyundai Service Bulletin HMC‑SB‑07‑018, is often linked to oil viscosity degradation or extended oil change intervals. From 2008 onward, Hyundai revised HLA materials and updated oil passage geometry to improve durability.
Hyundai
All production years 2005–2010 meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/6543).
The Hyundai G6CT is a 2,656 cc V6 naturally aspirated petrol engine engineered for mid-size sedans (2005–2010). It combines DOHC architecture with a Variable Intake System (VIS) to enhance mid-range torque and acoustic refinement. Designed to meet Euro 4 emissions standards, it balances smooth power delivery with long-term drivability and serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,656 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | V6, DOHC, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 83.0 mm × 82.0 mm | |
| Power output | 125–132 kW (170–180 PS) @ 6,000 rpm | |
| Torque | 245–255 Nm @ 4,000 rpm | |
| Fuel system | Sequential multi-point fuel injection (SFI) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.4:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain (dual chains, maintenance-free design) | |
| Oil type | Hyundai SP 5W‑30 (API SL/SM) | |
| Dry weight | 168 kg |
The V6 layout provides inherent balance and smoothness, but the hydraulic lash adjusters (HLAs) are sensitive to oil quality and change intervals. Using Hyundai SP 5W-30 (or ACEA A3/B4 equivalent) is essential to maintain HLA function and reduce ticking. The dual timing chains are maintenance-free but rely on consistent oil pressure; extended drain intervals increase wear risk. The VIS system improves mid-range torque but requires clean intake passages to operate correctly. Post-2008 engines feature updated HLAs per SIB HMC-SB-07-018.
Oil Specs: Requires Hyundai SP 5W-30 or ACEA A3/B4 (Hyundai SIB HMC-SB-07-018). Avoid low-SAPS or C3 oils.
Emissions: Euro 4 certification applies to all 2005–2010 G6CT engines (VCA Type Approval #VCA/EMS/6543). No Euro 5 variants exist.
Power Ratings: Measured under SAE J1349 standards. Output varies slightly by model calibration (Hyundai TIS Doc. G6CT-P105).
Hyundai Technical Information System (TIS): Docs G6CT-A101, G6CT-F201, G6CT-T301, SIB HMC-SB-07-018
VCA Type Approval Database (VCA/EMS/6543)
SAE International: J1349 Engine Power Certification Standards
The Hyundai G6CT was used across Hyundai's TG/NF platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced mounts in the Grandeur TG and revised intake manifolds in the Sonata NF—and from 2008 the updated HLA design improved cold-start quietness, creating minor ECU and parts interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front left side of the block near the timing cover (Hyundai TIS G6CT-ID01). The 7th VIN digit for G6CT is typically 'C' (e.g., KMHNF21CPGU123456). Early units (2005–2007) use silver valve covers with part number 21110-36000; post-2008 revisions use updated HLAs with part number 21110-36010. The intake manifold on Grandeur TG includes a dual-stage VIS actuator absent on early Sonata NF. ECU part numbers differ by model—ensure compatibility when swapping. No diesel variants share this code.
The G6CT's primary reliability risk is hydraulic lash adjuster (HLA) wear, with elevated incidence in high-mileage or poorly maintained engines. Hyundai internal data from 2009 indicated a notable share of 2005–2007 engines exhibiting valve train noise before 120,000 km, while UK DVSA records show few emissions-related failures due to robust catalytic design. Extended oil change intervals and urban driving increase HLA clogging risk, making oil quality and interval adherence critical.
Analysis derived from Hyundai technical bulletins (2007–2011) and UK DVSA failure statistics (2015–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HYUNDAI G6CT.
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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