Mercedes Fault Code List: Your Ultimate Diagnostic Guide

The Mercedes Fault Code List is an invaluable resource for diagnosing issues in your Mercedes-Benz. Understanding these diagnostic trouble codes, or DTCs, is crucial for both professional technicians and vehicle owners to efficiently troubleshoot problems. AutoExplain.com provides expert guidance and remote support to help you decode and resolve complex automotive issues, ensuring your Mercedes operates at its best. From powertrain malfunctions to body control module errors, we assist you with ECU remapping, module programming, and pinpointing potential problems within your vehicle’s systems.

1. Understanding Mercedes Fault Codes

Mercedes fault codes, also known as Diagnostic Trouble Codes (DTCs), are alphanumeric codes that the vehicle’s onboard computer stores when it detects a problem. These codes help identify the source of the issue, ranging from minor sensor malfunctions to critical system failures. The ability to accurately interpret these codes is essential for effective vehicle diagnostics and repair.

• OBD-II System: Modern Mercedes-Benz vehicles, manufactured after 1996, utilize an On-Board Diagnostics II (OBD-II) system. This standardized system allows technicians and owners to access fault codes using an OBD-II scanner.
• Accessing Fault Codes: Fault codes can be accessed by connecting an OBD-II scanner to the vehicle’s diagnostic port, typically located under the dashboard.

1.1. Decoding the Fault Code Structure

Understanding the structure of a Mercedes fault code is key to deciphering the problem. Each character in the code provides specific information about the fault’s location and type.

• First Character: Indicates the system where the fault occurred:

  • P (Powertrain): Relates to the engine, transmission, and associated components.
  • B (Body): Involves body-related systems like airbags, central locking, and power windows.
  • C (Chassis): Concerns chassis systems, including ABS (Anti-lock Braking System), ESP (Electronic Stability Program), and suspension.
  • U (Network/Communication): Pertains to communication networks within the vehicle, such as the CAN (Controller Area Network) bus.

• Second Character: Specifies whether the code is generic or manufacturer-specific:

  • 0: Generic OBD-II code (SAE standard).
  • 1, 2, or 3: Manufacturer-specific code (Mercedes-Benz).

• Third Character: Indicates the subsystem involved:

  • 1: Fuel and air metering.
  • 2: Fuel and air metering – injector circuit.
  • 3: Ignition system or misfires.
  • 4: Auxiliary emission controls.
  • 5: Vehicle speed control and idle control system.
  • 6: Computer output circuit.
  • 7: Transmission.

• Fourth and Fifth Characters: Provide more detail, pinpointing the exact nature of the fault.

1.2. Generic vs. Manufacturer-Specific Codes

It’s important to distinguish between generic (standardized) OBD-II codes and manufacturer-specific codes. Generic codes are common across different vehicle brands and can be diagnosed using standard OBD-II scanners. Manufacturer-specific codes, however, are unique to Mercedes-Benz and often require more specialized diagnostic tools and knowledge. AutoExplain.com can provide in-depth support for both types of codes, offering solutions for complex issues.

1.3. Common Fault Code Categories

Fault codes can be broadly categorized based on the affected system:

• Engine Fault Codes: These relate to engine performance, fuel delivery, ignition, and emission control systems. Examples include codes for misfires, oxygen sensor issues, and fuel trim problems.
• Transmission Fault Codes: These pertain to issues within the transmission system, such as gear ratio errors, solenoid malfunctions, and transmission fluid temperature problems.
• ABS/ESP Fault Codes: These involve the anti-lock braking system (ABS) and electronic stability program (ESP), covering wheel speed sensor faults, hydraulic modulator malfunctions, and control unit errors.
• Airbag Fault Codes: These concern the supplemental restraint system (SRS), including airbag sensor faults, airbag module malfunctions, and seatbelt pretensioner problems.
• Body Control Module (BCM) Fault Codes: These relate to various body-related functions, such as lighting, power windows, central locking, and wipers.
• Communication Network Fault Codes: These pertain to issues within the vehicle’s communication network, often involving the CAN bus system, which facilitates communication between different control units.
• AdBlue Fault Codes: These relate to the AdBlue system, covering issues with the AdBlue injector, AdBlue pump, AdBlue level sensor, and SCR catalytic converter.

2. Comprehensive List of Mercedes Fault Codes

Below is an extensive list of Mercedes-Benz fault codes, categorized for easier navigation. Note that this list is not exhaustive, and specific codes may vary depending on the model and year.

2.1. Powertrain (P) Codes

These codes relate to the engine, transmission, and associated components.