🏷️ Basic Information

Make:

Mercedes-Benz

Model:

S-Class

Chassis Code:

W221

Model Year:

2009

Generation Name:

Fourth Generation

Generation Years:

2005-2013

👋 Introduction

Market Segment:

Ultra-luxury sedan, flagship model of Mercedes-Benz.

Competitors:

BMW 7 Series, Audi A8, Lexus LS, Porsche Panamera.

Defining Attributes:

Unparalleled ride comfort, advanced safety and driver assistance technologies, sophisticated interior design and materials, powerful yet refined powertrains.

Target Audience:

Discerning individuals seeking the pinnacle of automotive luxury, comfort, and technological innovation.

📋 Manual Details

Coverage Description:

Comprehensive service, repair, and diagnostic procedures for the 2009 Mercedes-Benz S-Class W221, including all major mechanical, electrical, and body systems. Covers routine maintenance, troubleshooting, component replacement, and specialized repairs.

Estimated Page Count:

Over 3000 pages (typical for full factory service manuals of this era and complexity)

Manual Type:

Factory Service Repair Workshop Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine Mechanical:

Engine assembly, cylinder head, valve train, crankshaft, pistons, connecting rods, lubrication system, cooling system, engine management.

Engine Management Electronics:

Engine Control Unit (ECU) functions, sensor data, actuators, ignition system, fuel injection system, emissions control.

Transmission Mechanical:

Automatic transmission assembly (e.g., 7G-TRONIC), torque converter, planetary gear sets, hydraulic controls, clutch packs.

Transmission Electronics:

Transmission Control Unit (TCU), gear selection logic, shift solenoids, mechatronics unit.

Drivetrain:

Front axle, rear axle, drive shafts, differential, propeller shafts, transfer case (if applicable).

Suspension:

AIRMATIC dual control air suspension, Active Body Control (ABC) system, independent suspension components, control arms, ball joints, shock absorbers, air springs.

Steering:

Power steering system, steering column, steering gear, electronic power steering (EPS) components.

Brakes:

Hydraulic braking system, ABS (Anti-lock Braking System), ESP (Electronic Stability Program), brake boosters, master cylinder, brake calipers, rotors, brake pads, parking brake system (electronic).

Electrical System:

12V battery system, alternator, starter motor, wiring diagrams for all circuits, fuse boxes, relays.

Body And Chassis:

Body structure, doors, hood, trunk, bumpers, interior trim, exterior trim, noise insulation.

Comfort And Convenience:

Climate control system (THERMOTRONIC), power windows, power seats, sunroof, central locking, keyless entry, power trunk, soft-close doors.

Infotainment And Navigation:

COMAND (Cockpit Management and Navigation) system, audio system, navigation unit, telephone integration, media interface.

Lighting:

Headlights (bi-xenon, LED), taillights, interior lighting, fog lights, ambient lighting, headlight aiming.

Safety Systems:

AIRBAG system, seat belt pretensioners, occupant classification system, ABS, ESP, ADAPTIVE BRAKE, PRE-SAFE® system.

Driver Assistance:

DISTRONIC PLUS (adaptive cruise control), PARKTRONIC (parking assist), LANE KEEPING ASSIST, BLIND SPOT ASSIST, NIGHT VIEW ASSIST.

Routine Maintenance:

Oil changes, filter replacements (oil, air, cabin), fluid checks and top-offs, spark plug replacement, tire rotation, brake pad inspection.

Troubleshooting:

Diagnostic fault codes (DTCs), symptom-based troubleshooting guides, electrical circuit diagnosis, mechanical component diagnosis.

Component Replacement:

Detailed instructions for replacing major components like engine, transmission, starter, alternator, fuel pump, brake calipers, suspension struts, control modules.

Rebuilding Procedures:

Major overhaul procedures for engines and transmissions, including disassembly, inspection, component replacement, and reassembly.

Calibration And Adjustment:

Calibration of sensors (e.g., steering angle sensor, ride height sensors), alignment procedures, seat calibration, key programming.

Diagnostic Tool Usage:

Information on using Mercedes-Benz specific diagnostic tools (e.g., STAR DIAGNOSIS/XENTRY) for system analysis and module programming.

Depth Of Information:

Factory-level technical depth, including detailed schematics, torque specifications, clearances, diagnostic procedures, and component data.

📊 Manual Specifications

File Format:

PDF

Searchability:

Searchable text content for quick information retrieval.

Print Quality:

High-resolution, suitable for professional printing or on-screen viewing.

Binding Type:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Engine Options 2009:

S350 (3.5L V6 M272), S550 (5.5L V8 M273), S600 (5.5L V12 Bi-Turbo M275), S63 AMG (6.2L V8 M156), S65 AMG (6.0L V12 Bi-Turbo M275).

Engine Code S550:

M273

S550 Horsepower:

382 hp @ 6000 rpm

S550 Torque:

391 lb-ft @ 2800-4500 rpm

Fuel Type:

Premium Unleaded Gasoline (91 octane or higher recommended)

Injection Type:

Sequential Multi-Port Fuel Injection (MPI) or Direct Injection (DI) depending on specific engine variant.

Engine Control Module:

ME-SFI / ECM (Engine Control Module) / ECU

🔧 Transmission

Transmission Type S550:

7-speed automatic (7G-TRONIC)

All Wheel Drive:

4MATIC all-wheel drive available on select models (e.g., S550 4MATIC).

Transmission Modes:

Comfort (C) and Sport (S) modes.

Transmission Fluid Type:

MB Approved Automatic Transmission Fluid (ATF) such as MB 236.14 (e.g., Pentosin ATF1 or equivalent).

Transmission Fluid Capacity 7G Tronic:

Approx. 9 liters (2.4 US gallons) for a dry fill, consult manual for specific service fill.

📐 Dimensions

Wheelbase:

3165 mm (124.6 in)

Overall Length:

5207 mm (205.0 in)

Overall Width:

1871 mm (73.7 in)

Overall Height:

1477 mm (58.1 in)

Curb Weight S550:

Approx. 1990 kg (4387 lbs)

Gross Vehicle Weight Rating:

Consult vehicle placard

Standard Wheel Size:

18-inch alloy wheels

Standard Tire Size:

255/40 R18 (front and rear)

Wheel Bolt Pattern:

5x112

🛡️ Safety Features

NHTSA Front Crash Rating:

5-Star (typical for W221 era models)

IIHS Top Safety Pick:

Likely a Top Safety Pick recipient for its model year.

Active Safety Systems:

ABS, BAS (Brake Assist System), ESP, ASR (Acceleration Slip Regulation), Adaptive Brake Lights, PRE-SAFE® anticipatory safety system.

Driver Assistance Systems:

Optional DISTRONIC PLUS, LANE KEEPING ASSIST, BLIND SPOT ASSIST, NIGHT VIEW ASSIST, PARKTRONIC.

Passive Safety Features:

Advanced airbag system (front, side, curtain, knee), seatbelt pretensioners with force limiters, active head restraints.

💡 Technology Features

Infotainment System:

COMAND APS (Cockpit Management and Navigation) with integrated navigation, AM/FM/Weather band radio, CD/DVD changer, MP3 capability, optional Harman Kardon surround sound audio system.

Display:

Large central LCD display.

Adaptive Cruise Control:

Optional DISTRONIC PLUS system with radar-based adaptive cruise control and braking functionality.

Parking Assistance:

Optional PARKTRONIC parking assist system with ultrasonic sensors and visual/audible alerts.

Phone Integration:

Bluetooth connectivity for hands-free calling and phone book access.

Media Interface:

Optional Media Interface for connecting external media devices (e.g., iPod).

Climate Control:

THERMOTRONIC automatic climate control with multiple climate zones.

Suspension Technology:

AIRMATIC dual control air suspension, optional Active Body Control (ABC) for superior ride and handling.

🔧 Maintenance

Service A Interval:

Typically every 10,000 miles or 12 months, whichever comes first (indicated by the 'Service A' message on the dashboard).

Service B Interval:

Typically every 20,000 miles or 24 months, whichever comes first (indicated by the 'Service B' message on the dashboard).

Engine Oil Specification:

MB 229.5 or MB 229.51 approved synthetic oil, typically 0W-40 or 5W-40 viscosity grade (check manual for specific engine variant).

Engine Oil Capacity S550:

Approx. 8.0 liters (8.5 US quarts) with filter change.

Coolant Specification:

MB Approved Antifreeze/Coolant, such as MB 325.0 or MB 326.0 (typically a 50/50 mix with distilled water).

Brake Fluid Specification:

DOT 4 Plus (MB Spec 331.0) or equivalent.

Common Issues Suspension:

AIRMATIC suspension leaks (struts, lines), ABC system hydraulic leaks and pump failures, control arm bushing wear.

Common Issues Electronics:

EIS (Electronic Ignition Switch) failure, SAM (Signal Acquisition and Actuation) module issues, CAN bus communication errors, COMAND system glitches.

Common Issues Engine:

M272/M273 intake manifold runner flap failure, oil cooler leaks, camshaft position sensor failures.

Common Issues Transmission:

7G-TRONIC mechatronics unit issues, torque converter problems, transmission fluid leaks.

📚 Vehicle History

Brand Legacy:

Mercedes-Benz has a long-standing reputation for producing luxurious, technologically advanced, and robust vehicles, with the S-Class being its flagship and a benchmark for automotive innovation.

W221 Introduction:

The W221 S-Class was introduced in 2005 as a successor to the W220, representing a significant step forward in design, technology, and safety.

W221 Facelift:

The W221 received a significant facelift for the 2010 model year, with updates to styling, powertrain, and technology. The 2009 model represents the pre-facelift version.

Production Location:

Sindelfingen, Germany

🏆 Awards & Recognition

Historical Recognition:

The S-Class consistently receives accolades for safety, luxury, and innovation from various automotive publications and organizations.

Consumer Reports Rating:

Historically, the S-Class has been rated highly for its comfort and performance, though complex electronics can sometimes lead to average predicted reliability scores. Consult specific year reviews for detailed ratings.

Safety Certifications:

Certified to meet all relevant federal motor vehicle safety standards (FMVSS) for its model year.