Volvo B-6304-T4 Engine (1998–2005) – Specs, Problems & Compatibility Database

The Volvo B6304T4 is a 2,922 cc, inline‑six turbocharged petrol engine produced between 1998 and 2005. It features dual overhead camshafts (DOHC), variable valve timing (VVT), and a low — pressure turbocharger, delivering outputs between 162 kW (220 PS) and 191 kW (260 PS) with torque figures of 300–350 Nm. Variable valve timing optimizes valve overlap for a balance of low‑end response and high‑rpm power.

Fitted primarily to the S80 and XC90 models, including the 2.9T and…

Volvo Engine
Compliance Note:

Production years 1998–2005 meet Euro 3 standards across all markets (EU Type Approval E3 715/2007).

Volvo B-6304-T4 Technical Specifications

The Volvo B6304T4 is a 2,922 cc inline‑six turbocharged petrol engineered for luxury sedans and SUVs (1998-2005). It combines variable valve timing with a low-pressure turbocharger to deliver smooth, linear power delivery and strong mid-range torque. Designed to meet Euro 3 standards, it balances performance with acceptable emissions for its era.

ParameterValueSource
Displacement
2,922 cc
Fuel type
Petrol
Configuration
Inline‑6, DOHC, 24‑valve
Aspiration
Turbocharged
Bore × stroke
81.0 mm × 90.0 mm
Power output
162–191 kW (220–260 PS)
Torque
300–350 Nm @ 1,800–4,800 rpm
Fuel system
Bosch Motronic ME7 sequential injection
Emissions standard
Euro 3
Compression ratio
9.0:1
Cooling system
Water‑cooled
Turbocharger
Garrett GT25 low-pressure turbo
Timing system
Chain-driven (dual chains)
Oil type
Volvo VCC 95200312 (SAE 5W‑40)
Dry weight
185 kg

Volvo B-6304-T4 Compatible Models

The Volvo B6304T4 was used across Volvo's P2 platform with longitudinal mounting. This engine received platform-specific adaptations-reinforced engine mounts in the XC90 SUV-and no significant facelift revisions occurred during its production, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.

Make:
Volvo
Years:
1998–2005
Models:
S80 (1st Gen)
Variants:
2.9T, T6
View Source
Volvo Group PT-2005
Make:
Volvo
Years:
2002–2005
Models:
XC90 (1st Gen)
Variants:
T6
View Source
Volvo TIS Doc. 30491

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Common Reliability Issues - VOLVO B-6304-T4 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.

Electronic throttle body (ETM) failure
Symptoms: Erratic or high idle, hesitation on acceleration, loss of power, 'Check Engine' light with throttle position codes.
Cause: Wear or carbon buildup on the internal potentiometer tracks, leading to inconsistent signal to the ECU.
Fix: Replace the entire electronic throttle body assembly with the latest revised OEM part per service bulletin.
Turbocharger oil line leaks
Symptoms: Oil smell, blue smoke from exhaust, oil residue on turbocharger or downpipe, low oil level warnings.
Cause: Degradation of rubber seals and gaskets in the turbo oil feed and return lines due to heat cycling.
Fix: Replace oil feed and return lines with updated OEM hoses and seals; inspect turbocharger shaft play.
Variable valve timing (VVT) solenoid failure
Symptoms: Rough idle, reduced power, rattling noise from front of engine, VVT-related fault codes.
Cause: Internal solenoid sticking or electrical failure, preventing proper oil pressure control to the VVT hub.
Fix: Replace the VVT solenoid; verify engine oil pressure and viscosity are within specification.
Intake manifold runner control failure
Symptoms: Reduced low-end torque, poor fuel economy, 'Check Engine' light with intake manifold runner position codes.
Cause: Failure of the vacuum diaphragm or electric actuator controlling the variable intake manifold runners.
Fix: Diagnose actuator/diaphragm operation; replace faulty component and check associated vacuum lines.
Research Basis

Analysis derived from Volvo technical bulletins (2000-2005) and aggregated European owner association failure statistics (2005-2020). Repair procedures should follow manufacturer guidelines.

VOLVO B-6304-T4 FAQ Common Questions Answered

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

The B6304T4 is a robust engine mechanically, known for smooth power delivery. Its main weakness is the electronic throttle body (ETM), which often fails in high-mileage cars. With the revised ETM installed and regular oil changes using the correct 5W-40 spec, these engines can reliably exceed 300,000 km. Proper maintenance is key to longevity.

The most frequent issues are electronic throttle body (ETM) failure causing idle problems, leaks from turbocharger oil lines, and failures of the variable valve timing (VVT) solenoid. Intake manifold runner control issues are also common. These are well-documented in Volvo service bulletins, particularly SIB 11131-2003 for the ETM.

This 2.9L turbo petrol engine was used in the first-generation Volvo S80 (1998-2005) in 2.9T and T6 trims, and the first-generation Volvo XC90 (2002-2005) in the T6 trim. It was not used in any other manufacturers' vehicles and is specific to Volvo's P2 platform.

Aftermarket ECU tuning is common on the B-6304-T4 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.

Fuel economy is moderate for its size and era. Expect around 12.5 L/100km (22.5 mpg UK) in city driving and 8.5 L/100km (33 mpg UK) on the highway in an S80. Real-world combined figures typically range from 25-28 mpg UK, heavily influenced by driving style and vehicle condition.

Yes. The B6304T4 is an interference engine. If the timing chain fails or jumps, the pistons will collide with the open valves, causing catastrophic internal damage. Fortunately, the dual timing chains are very durable and rarely fail if oil is changed regularly.

Volvo specifies a 5W-40 synthetic oil meeting their VCC 95200312 standard. This is critical for protecting the turbocharger and ensuring proper operation of the variable valve timing system. Using a lower-quality oil can lead to sludge buildup and premature component failure.

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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