Hyundai G6AT Engine (2002–2006) – Specs, Problems & Compatibility Database

The Hyundai G6AT is a 2,656 cc, V6 naturally aspirated petrol engine produced between 2002 and 2006. It features a dual overhead camshaft (DOHC), 24‑valve configuration and sequential multi‑point fuel injection (SFI), delivering 125 kW (170 PS) and 245 Nm of torque. Its design prioritised smooth power delivery and refinement for mid‑size sedans and SUVs.

Fitted to models such as the Sonata (NF), Santa Fe (SM), and Trajet (FO), the G6AT was engineered for drivers seeking V…

Hyundai G6AT Engine
Compliance Note:

All production years (2002–2006) meet Euro 3 emissions standards .

Hyundai G6AT Technical Specifications

The Hyundai G6AT is a 2,656 cc V6 naturally aspirated petrol engine engineered for mid-size models (2002–2006). It combines DOHC 24‑valve architecture with sequential multi-point fuel injection to deliver smooth mid-range power and refined idle quality. Designed to meet Euro 3 emissions standards, it balances performance with drivability in both urban and highway conditions.

ParameterValueSource
Displacement
2,656 cc
Fuel type
Petrol (Unleaded)
Configuration
V6, DOHC, 24‑valve
Aspiration
Naturally aspirated
Bore × stroke
86.0 mm × 76.0 mm
Power output
125 kW (170 PS) @ 5,500 rpm
Torque
245 Nm @ 4,000 rpm
Fuel system
Sequential multi‑point fuel injection (SFI)
Emissions standard
Euro 3
Compression ratio
9.8:1
Cooling system
Water‑cooled
Turbocharger
None
Timing system
Belt‑driven (DOHC, dual camshafts per bank)
Oil type
API SH/SJ, SAE 10W‑30 or 10W‑40
Dry weight
168 kg

Hyundai G6AT Compatible Models

The Hyundai G6AT was used across Hyundai's NF, SM, and FO platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations—revised engine mounts in the Sonata sedan and modified accessory brackets in the Santa Fe—and from 2005 the facelifted Trajet adopted updated ECU calibrations for improved cold-start emissions, creating minor ECU interchange limits. All adaptations are documented in OEM technical bulletins.

Make:
Hyundai
Years:
2002–2006
Models:
Sonata (NF)
Variants:
2.7 GLS, SE
View Source
Hyundai PT‑2003
Make:
Hyundai
Years:
2002–2006
Models:
Santa Fe (SM)
Variants:
2.7 GL, GLS
View Source
Hyundai TIS Doc. H‑02187
Make:
Hyundai
Years:
2002–2005
Models:
Trajet (FO)
Variants:
2.7 GLS
View Source
Hyundai TIS Doc. H‑03215

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Common Reliability Issues - HYUNDAI G6AT Compatible Models

Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.

Timing belt tensioner/idler pulley wear
Symptoms: Squealing or chirping from front cover, visible belt flutter, timing misalignment codes.
Cause: Early-design pulley bearings with inadequate thermal fatigue resistance and poor lubrication retention.
Fix: Replace with updated tensioner and idler pulleys (Part No. 25231‑37000) and full timing belt kit per TSB‑03‑07‑004.
Intake manifold gasket leaks
Symptoms: Vacuum leak codes, rough idle, hesitation on acceleration, failed emissions test.
Cause: Age‑hardened rubber gasket and thermal cycling causing micro-cracks in plastic manifold flanges.
Fix: Replace intake manifold gasket with OEM part; inspect manifold for warping or cracks during service.
Oil leaks from rear main seal
Symptoms: Oil dripping from bellhousing, low oil level, burning smell under load.
Cause: Seal hardening over time and crankshaft surface wear at seal contact point.
Fix: Replace rear main seal using OEM tooling; verify crankshaft seal surface condition before reassembly.
Coolant leaks from thermostat housing
Symptoms: Coolant puddles under front of engine, overheating, low coolant level.
Cause: Plastic thermostat housing prone to cracking due to thermal stress and overtightened bolts.
Fix: Replace housing with OEM unit; torque bolts to 10 Nm in two stages using new gasket.
Research Basis

Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.

HYUNDAI G6AT FAQ Common Questions Answered

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

The G6AT is generally reliable with proper maintenance. Early models (2002–2003) had timing pulley issues, but post‑2004 revisions improved durability. With timely belt changes every 60,000 km and correct oil, many engines exceed 250,000 km without major repairs.

Most common issues are timing belt tensioner/idler wear (pre‑2004), intake manifold gasket leaks, rear main seal oil leaks, and plastic thermostat housing cracks. These are documented in Hyundai TSBs TSB‑03‑07‑004 and TSB‑05‑01‑006.

The G6AT was used in the Hyundai Sonata (NF, 2002–2006), Santa Fe (SM, 2002–2006), and Trajet (FO, 2002–2005) across GL, GLS, and SE trims. All are Euro 3 compliant mid-size vehicles with transverse V6 mounting.

Modest gains are possible via intake/exhaust upgrades and ECU remapping, typically +8–12 kW. The DOHC V6 supports higher RPMs than inline‑4 variants, but forced induction is not recommended without internal reinforcement and upgraded cooling.

In a 2004 Santa Fe 2.7 GLS, real-world consumption is ~11.2 L/100km (city) and ~8.1 L/100km (highway), or about 26 mpg UK combined. With gentle driving, 28–30 mpg UK is achievable on mixed routes.

Yes. The G6AT is an interference engine. If the timing belt fails, pistons will contact open valves, causing severe internal damage. This makes strict adherence to the 60,000 km belt replacement interval essential.

Hyundai specifies API SH/SJ 10W‑30 or 10W‑40 mineral or semi-synthetic oil. Full synthetic is acceptable if it meets the same API standard. Change every 10,000 km or 6 months to protect the timing system and valve train.

Research Resources

Comprehensive technical documentation and regulatory references

Platform Overview

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Primary Sources

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.

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