Understanding Mercedes-Benz Service Codes: A0–A9, B0–B9 & What They Mean

At NV Euro Motor Works, we specialize in Mercedes-Benz service and repair using factory-trained technicians and advanced Mercedes-Benz diagnostic tools like XENTRY. One of the most common questions our customers ask is: “What do all these A and B service codes mean on my Mercedes dashboard?”

If you're a Mercedes owner in need of routine maintenance, understanding these codes can help you stay ahead of costly repairs and preserve your vehicle’s peak performance.

🛠️ What Are Mercedes-Benz Service Codes?

Mercedes-Benz uses Service Codes—such as A0, A1, B0, B1, etc.—to indicate what kind of scheduled maintenance your vehicle requires. These alerts appear on your dash when it's time for service. Each code represents a specific set of tasks, allowing technicians and owners to stay aligned on what the vehicle needs.

These service intervals are essential for:

• Maintaining warranty coverage
• Enhancing performance and efficiency
• Preventing breakdowns and premature wear

Let’s break down what each A-Series and B-Series code means so you can better understand your vehicle’s needs.

✅ A-Series Service Codes (Basic Service Plus Targeted Add-Ons)

🔧 A0 – Basic Service A

Includes:

• Synthetic oil and filter replacement
• Resetting service counter
• Multi-point safety inspection

🌀 A1 – Cabin Dust/Combination Filter

• Replaces your interior AC/pollen air filter

⚙️ A3 – Transmission Service

• Replace automatic transmission fluid and filter (if applicable)

🔥 A4 – Spark Plug Service

• Replace spark plugs (typically every 60,000 miles or 100,000 km)

🌬️ A6 – Engine Air Filter

• Replace engine air filter to ensure clean airflow and performance

🛑 A7 – Brake Fluid Replacement

• Flush and replace brake fluid to maintain optimal braking response

⚖️ A8 – Differential Service

• Replace differential fluid (especially in 4MATIC and AMG models)

⛽ A9 – Fuel Filter Replacement

• Replace fuel filter (diesel and select gasoline models)

🔎 Additional A-Series Codes

🌫️ AC – Emissions Check

• Inspect emissions-related components and software

🔁 AF – Transfer Case Fluid

• Replace transfer case fluid (for 4MATIC systems)

⚡ AH – High Voltage Check

• Inspect high-voltage components in EQ hybrid and electric models

❄️ AG – Cooling System Service

• Check coolant levels and hoses; flush if necessary

🧰 AK – Drive Belt Inspection/Replacement

• Inspect or replace serpentine belt (drives AC, alternator, etc.)

🔧 B-Series Service Codes (A0 + Enhanced Maintenance)

🛠️ B0 – Basic Service B

Includes everything in A0, plus:

• In-depth inspection of brakes, suspension, tires, and fluids

🧼 B1 – Cabin Filter + Brake Inspection

• Replace cabin filter
• Inspect brake pads, rotors, and calipers

🛞 B2 – Engine Air Filter

• Replace engine air filter for fuel efficiency and performance

⚙️ B3 – Transmission Fluid Service

• Replace fluid, inspect, and reset transmission adaptation

🔌 B4 – Spark Plugs & Ignition Check

• Replace spark plugs and inspect ignition system

⛽ B5 – Fuel Filter

• Replace fuel filter (as needed per model)

⚖️ B6 – Drivetrain Fluids

• Replace differential and transfer case fluids

🛑 B7 – Brake Fluid Service

• Flush and refill brake fluid for safe braking

💧 B8 – Coolant Flush

• Full cooling system flush and refill

🚿 B9 – Fuel Injection Cleaning

• Clean fuel injection system (optional based on vehicle condition)

🧪 Specialized B-Series Diagnostics

🧾 BD – Diagnostic Services

• Scan and clear trouble codes using XENTRY

🔥 BE – Exhaust System Inspection

• Inspect exhaust, catalytic converter, and emissions components

🔑 BK – Key Fob Battery & Programming

• Replace battery, test remote functionality

🛞 BS – Suspension Check

• Inspect suspension components including shocks, struts, bushings

🧰 Why Trust NV Euro Motor Works for Your Mercedes-Benz Service?

At NV Euro Motor Works, we understand the intricacies of your luxury vehicle. Our shop uses Mercedes-Benz-approved diagnostic tools, follows OEM guidelines, and delivers personalized service without dealership pricing.

Benefits of choosing us:

• Factory-trained Mercedes technicians
• Advanced diagnostics (XENTRY)
• Transparent recommendations
• No unnecessary upselling
• Service tailored to your model and driving habits

📅 Stay Ahead of the Dashboard Warnings

If your Mercedes is displaying a service code or you're unsure which service is due, our expert team is here to help. We’ll decode the message, perform only what your vehicle truly needs, and keep you informed every step of the way.

👉 Serving Mercedes-Benz owners in Markham, ON with excellence and integrity.

Book your Mercedes-Benz service today with NV Euro Motor Works—where expertise meets peace of mind.