How To Read Mercedes Codes: A Comprehensive Guide

How To Read Mercedes Codes accurately is crucial for diagnosing and repairing your vehicle effectively. At AutoExplain.com, we provide the expertise and remote support you need to decipher these codes and address underlying issues, ensuring optimal performance and longevity for your Mercedes-Benz, and give solutions of car computer reading and error code interpretations. With our support, you can confidently tackle any diagnostic challenge.

1. Understanding Mercedes-Benz Diagnostic Trouble Codes (DTCs)

Mercedes-Benz vehicles are equipped with sophisticated onboard computer systems that monitor numerous systems, sensors, and variables. When a problem arises, the system generates a Diagnostic Trouble Code (DTC), commonly referred to as a fault code. These codes are designed to help technicians diagnose issues by providing a specific indication of where the problem lies. Understanding how to read and interpret these codes is the first step in effective Mercedes-Benz diagnostics and troubleshooting.

1.1. What is a Fault Code?

A fault code, or DTC, is a system-generated error code that alerts you to a malfunctioning component or system within your Mercedes. These codes are essential for identifying and addressing the root cause of a problem. When your Mercedes detects an issue, it stores a corresponding fault code in its onboard computer.

1.2. The Importance of Diagnostic Trouble Codes (DTCs)

DTCs provide a standardized way to identify and understand issues within a vehicle’s systems. They act as a guide, pointing technicians to the specific area where a problem exists. Without these codes, diagnosing issues would be significantly more time-consuming and challenging.

1.3. Common Mercedes Error Messages

Mercedes-Benz vehicles can display a variety of error messages, each indicating a specific issue. These messages often appear on the dashboard, alerting the driver to potential problems that need attention. Here are some common error messages you might encounter:

• Check Engine Light: Indicates an issue within the engine or related systems.
• Brake Warning Light: Signifies a problem with the braking system.
• Temperature Warning Light: Alerts to potential engine overheating.
• ABS Warning Light: Indicates an issue with the Anti-lock Braking System.
• SRS Warning Light: Signifies a problem with the Supplemental Restraint System (airbags).
• Tyre Pressure Warning Light: Alerts to low or inconsistent tire pressure.

1.4. Decoding Mercedes-Benz Fault Codes

Mercedes-Benz fault codes typically follow a standardized format, consisting of a letter followed by four or five numbers. The letter indicates the system or area of the vehicle where the fault originated.

• P (Powertrain): Relates to the engine, transmission, and related components.
• B (Body): Involves body-related systems such as airbags, central locking, and windows.
• C (Chassis): Pertains to chassis systems like ABS, ESP, and suspension.
• U (Network/Communication): Indicates issues with the vehicle’s communication network.

The numbers provide more specific information about the nature and location of the fault. For instance, P0300 indicates a random or multiple cylinder misfire, while B1000 might indicate a low supply voltage to the headlamp range adjustment control unit.

2. Essential Tools for Reading Mercedes Codes

To effectively read Mercedes codes, you’ll need the right tools. These tools allow you to access the information stored in the vehicle’s onboard computer and retrieve the fault codes that can guide your diagnostic efforts.

2.1. OBD-II Scanners

An OBD-II scanner is the primary tool for reading Mercedes codes. These scanners connect to the vehicle’s OBD-II port, typically located under the dashboard, and retrieve diagnostic information. There are various types of OBD-II scanners available, ranging from basic code readers to advanced diagnostic tools.

Alt text: Mercedes-Benz OBD-II scanner connected to the vehicle’s diagnostic port, showing the display with diagnostic trouble codes.

2.2. Advanced Diagnostic Equipment

For more in-depth diagnostics, advanced equipment is necessary. Tools like the Mercedes-Benz Star Diagnosis system or Autel diagnostic scanners provide comprehensive access to the vehicle’s systems, allowing you to read fault codes, view live data, perform component testing, and even program control units.

2.3. Software and Apps

In addition to physical scanners, various software and mobile apps can be used to read Mercedes codes. These apps often work in conjunction with a Bluetooth or Wi-Fi OBD-II adapter that plugs into the vehicle’s diagnostic port. Popular apps include Torque Pro, OBD Fusion, and Carly for Mercedes.

3. Step-by-Step Guide: How to Read Mercedes Codes

Reading Mercedes codes involves a series of straightforward steps. Here’s a detailed guide on how to use an OBD-II scanner to retrieve fault codes from your vehicle:

3.1. Locating the OBD-II Port

The first step is to locate the OBD-II port in your Mercedes-Benz. The port is usually found under the dashboard on the driver’s side. It may be covered by a small panel that needs to be opened or removed.

3.2. Connecting the Scanner

Once you’ve located the OBD-II port, plug your scanner into the port. Ensure that the connection is secure and that the scanner is properly seated.

3.3. Turning on the Ignition

With the scanner connected, turn on the vehicle’s ignition to the “on” position. This provides power to the scanner and allows it to communicate with the vehicle’s computer. You don’t need to start the engine; simply turn the key to the position just before starting.

3.4. Reading the Codes

Follow the scanner’s instructions to read the codes. Most scanners have a “Read Codes” or “Diagnostic Codes” option in their menu. Select this option, and the scanner will retrieve the fault codes stored in the vehicle’s computer.

3.5. Interpreting the Codes

Once the scanner has retrieved the codes, it will display them on the screen. Note down the codes and their descriptions. Refer to a Mercedes-Benz fault code database or consult with a professional to understand the meaning of each code.

3.6. Clearing the Codes (Optional)

After addressing the underlying issue, you can clear the codes using the scanner. However, it’s essential to ensure that the problem has been resolved before clearing the codes. Clearing codes without fixing the issue will only result in the codes reappearing.

4. Common Mercedes Fault Codes and Their Meanings

Understanding common Mercedes fault codes can help you quickly identify and address issues with your vehicle. Here are some frequently encountered codes and their potential meanings:

4.1. P0400 Series: Exhaust Gas Recirculation (EGR) Issues

The P0400 series of codes relates to the Exhaust Gas Recirculation (EGR) system, which helps reduce emissions by recirculating exhaust gases back into the engine.

Mercedes Fault Code	Fault Code Meaning
P0466	Purge Flow Sensor Circuit Range/Performance
P0467	Purge Flow Sensor Circuit Low Input
P0468	Purge Flow Sensor Circuit High Input
P0469	Purge Flow Sensor Circuit Intermittent
P0470	Exhaust Pressure Sensor Malfunction
P0471	Exhaust Pressure Sensor Range/Performance
P0472	Exhaust Pressure Sensor Low
P0473	Exhaust Pressure Sensor High
P0474	Exhaust Pressure Sensor Intermittent
P0475	Exhaust Pressure Control Valve Malfunction
P0476	Exhaust Pressure Control Valve Range/Performance
P0477	Exhaust Pressure Control Valve Low
P0478	Exhaust Pressure Control Valve High
P0479	Exhaust Pressure Control Valve Intermittent
P0480	Cooling Fan 1 Control Circuit Malfunction
P0481	Cooling Fan 2 Control Circuit Malfunction
P0482	Cooling Fan 3 Control Circuit Malfunction
P0483	Cooling Fan Rationality Check Malfunction
P0484	Cooling Fan Circuit Over Current
P0485	Cooling Fan Power/Ground Circuit Malfunction

4.2. P0500 Series: Vehicle Speed Sensor (VSS) Problems

The P0500 series of codes pertains to the Vehicle Speed Sensor (VSS), which measures the speed of the vehicle.

Mercedes Fault Code	Fault Code Meaning
P0500	Vehicle Speed Sensor Malfunction
P0501	Vehicle Speed Sensor Range/Performance
P0502	Vehicle Speed Sensor Low Input
P0503	Vehicle Speed Sensor Intermittent/Erratic/High
P0505	Idle Control System Malfunction
P0506	Idle Control System RPM Lower Than Expected
P0507	Idle Control System RPM Higher Than Expected
P0510	Closed Throttle Position Switch Malfunction
P0520	Engine Oil Pressure Sensor/Switch Circuit Malfunction
P0521	Engine Oil Pressure Sensor/Switch Circuit Range/Performance
P0522	Engine Oil Pressure Sensor/Switch Circuit Low Voltage
P0523	Engine Oil Pressure Sensor/Switch Circuit High Voltage
P0530	A/C Refrigerant Pressure Sensor Circuit Malfunction
P0531	A/C Refrigerant Pressure Sensor Circuit Range/Performance
P0532	A/C Refrigerant Pressure Sensor Circuit Low Input
P0533	A/C Refrigerant Pressure Sensor Circuit High Input
P0534	Air Conditioner Refrigerant Charge Loss
P0550	Power Steering Pressure Sensor Circuit Malfunction
P0551	Power Steering Pressure Sensor Circuit Range/Performance
P0552	Power Steering Pressure Sensor Circuit Low Input
P0553	Power Steering Pressure Sensor Circuit High Input
P0554	Power Steering Pressure Sensor Circuit Intermittent
P0560	System Voltage Malfunction
P0561	System Voltage Unstable
P0562	System Voltage Low
P0563	System Voltage High
P0565	Cruise Control On Signal Malfunction
P0566	Cruise Control Off Signal Malfunction
P0567	Cruise Control Resume Signal Malfunction
P0568	Cruise Control Set Signal Malfunction
P0569	Cruise Control Coast Signal Malfunction
P0570	Cruise Control Accel Signal Malfunction
P0571	Cruise Control/Brake Switch A Circuit Malfunction
P0572	Cruise Control/Brake Switch A Circuit Low
P0573	Cruise Control/Brake Switch A Circuit High
P0574	Cruise Control Related Malfunction
P0575	Cruise Control Related Malfunction
P0576	Cruise Control Related Malfunction
P0576	Cruise Control Related Malfunction
P0578	Cruise Control Related Malfunction
P0579	Cruise Control Related Malfunction
P0580	Cruise Control Related Malfunction

4.3. P0600 Series: Control Module Issues

The P0600 series of codes indicates problems with the vehicle’s control modules, which are responsible for managing various systems.

Mercedes Fault Code	Fault Code Meaning
P0600	Serial Communication Link Malfunction
P0601	Internal Control Module Memory Check Sum Error
P0602	Control Module Programming Error
P0603	Internal Control Module Keep Alive Memory (KAM) Error
P0604	Internal Control Module Random Access Memory (RAM) Error
P0605	Internal Control Module Read Only Memory (ROM) Error
P0606	PCM Processor Fault
P0608	Control Module VSS Output “A” Malfunction
P0609	Control Module VSS Output “B” Malfunction
P0620	Generator Control Circuit Malfunction
P0621	Generator Lamp “L” Control Circuit Malfunction
P0622	Generator Field “F” Control Circuit Malfunction
P0650	Malfunction Indicator Lamp (MIL) Control Circuit Malfunction
P0654	Engine RPM Output Circuit Malfunction
P0655	Engine Hot Lamp Output Control Circuit Malfunction
P0656	Fuel Level Output Circuit Malfunction

4.4. P0700 Series: Transmission Problems

The P0700 series of codes relates to the transmission system, indicating issues such as incorrect gear ratios, solenoid malfunctions, or temperature sensor problems.

Mercedes Fault Code	Fault Code Meaning
P0700	Transmission Control System Malfunction
P0701	Transmission Control System Range/Performance
P0702	Transmission Control System Electrical
P0703	Torque Converter/Brake Switch B Circuit Malfunction
P0704	Clutch Switch Input Circuit Malfunction
P0705	Transmission Range Sensor Circuit malfunction (PRNDL Input)
P0706	Transmission Range Sensor Circuit Range/Performance
P0707	Transmission Range Sensor Circuit Low Input
P0708	Transmission Range Sensor Circuit High Input
P0709	Transmission Range Sensor Circuit Intermittent
P0710	Transmission Fluid Temperature Sensor Circuit Malfunction
P0711	Transmission Fluid Temperature Sensor Circuit Range/Performance
P0712	Transmission Fluid Temperature Sensor Circuit Low Input
P0713	Transmission Fluid Temperature Sensor Circuit High Input
P0714	Transmission Fluid Temperature Sensor Circuit Intermittent
P0715	Input/Turbine Speed Sensor Circuit Malfunction
P0716	Input/Turbine Speed Sensor Circuit Range/Performance
P0717	Input/Turbine Speed Sensor Circuit No Signal
P0718	Input/Turbine Speed Sensor Circuit Intermittent
P0719	Torque Converter/Brake Switch B Circuit Low
P0720	Output Speed Sensor Circuit Malfunction
P0721	Output Speed Sensor Range/Performance
P0722	Output Speed Sensor No Signal
P0723	Output Speed Sensor Intermittent
P0724	Torque Converter/Brake Switch B Circuit High
P0725	Engine Speed input Circuit Malfunction
P0726	Engine Speed Input Circuit Range/Performance
P0727	Engine Speed Input Circuit No Signal
P0728	Engine Speed Input Circuit Intermittent
P0730	Incorrect Gear Ratio
P0731	Gear 1 Incorrect Ratio
P0732	Gear 2 Incorrect Ratio
P0733	Gear 3 Incorrect Ratio
P0734	Gear 4 Incorrect Ratio
P0735	Gear 5 Incorrect Ratio
P0736	Reverse Incorrect Gear Ratio
P0740	Torque Converter Clutch Circuit Malfuction
P0741	Torque Converter Clutch Circuit Performance or Stuck Off
P0742	Torque Converter Clutch Circuit Stuck On
P0743	Torque Converter Clutch Circuit Electrical
P0744	Torque Converter Clutch Circuit Intermittent
P0745	Pressure Control Solenoid Malfunction
P0746	Pressure Control Solenoid Performance or Stuck Off
P0747	Pressure Control Solenoid Stuck On
P0748	Pressure Control Solenoid Electrical
P0749	Pressure Control Solenoid Intermittent
P0750	Shift Solenoid A Malfunction
P0751	Shift Solenoid A Performance or Stuck Off
P0752	Shift Solenoid A Stuck On
P0753	Shift Solenoid A Electrical
P0754	Shift Solenoid A Intermittent
P0755	Shift Solenoid B Malfunction
P0756	Shift Solenoid B Performance or Stuck Off
P0757	Shift Solenoid B Stuck On
P0758	Shift Solenoid B Electrical
P0759	Shift Solenoid B Intermittent
P0760	Shift Solenoid C Malfunction
P0761	Shift Solenoid C Performance or Stuck Off
P0762	Shift Solenoid C Stuck On
P0763	Shift Solenoid C Electrical
P0764	Shift Solenoid C Intermittent
P0765	Shift Solenoid D Malfunction
P0766	Shift Solenoid D Performance or Stuck Off
P0767	Shift Solenoid D Stuck On
P0768	Shift Solenoid D Electrical
P0769	Shift Solenoid D Intermittent
P0770	Shift Solenoid E Malfunction
P0771	Shift Solenoid E Performance or Stuck Off
P0772	Shift Solenoid E Stuck On
P0773	Shift Solenoid E Electrical
P0774	Shift Solenoid E Intermittent
P0780	Shift Malfunction
P0781	1-2 Shift Malfunction
P0782	2-3 Shift Malfunction
P0783	3-4 Shift Malfunction
P0784	4-5 Shift Malfunction
P0785	Shift/Timing Solenoid Malfunction
P0786	Shift/Timing Solenoid Range/Performance
P0787	Shift/Timing Solenoid Low
P0788	Shift/Timing Solenoid High
P0789	Shift/Timing Solenoid Intermittent
P0790	Normal/Performance Switch Circuit Malfunction

4.5. P0800 Series: Transmission Control System

The P0800 series of codes relates to issues within the transmission control system, including problems with shift solenoids, clutch position sensors, and gear lever sensors.

Mercedes Fault Code	Fault Code Meaning
P0801	Reverse Inhibit Control Circuit Malfunction
P0803	1-4 Upshift (Skip Shift) Solenoid Control Circuit Malfunction
P0804	1-4 Upshift (Skip Shift) Lamp Control Circuit Malfunction
P0805	Clutch Position Sensor Circuit Malfunction
P0806	Clutch Position Sensor Circuit Range/Performance
P0807	Clutch Position Sensor Circuit Low
P0808	Clutch Position Sensor Circuit High
P0809	Clutch Position Sensor Circuit Intermittent Ckt
P0810	Clutch Position Control Malfunction
P0811	Clutch Slippage Excessive
P0812	Reverse Input Circuit Malfunction
P0813	Reverse Output Circuit Malfunction
P0814	Trans Range Display Circuit Malfunction
P0815	Upshift Switch Circuit Malfunction
P0816	Downshift Switch Circuit Malfunction
P0817	Starter Disable Circuit
P0818	Driveline Disconn. Switch Input
P0820	Gear Lever X-Y Sensor Circuit
P0821	Gear Lever X Sensor Circuit
P0822	Gear Lever Y Sensor Circuit
P0823	Gear Lever X Sensor Circuit Intermittent Ckt
P0824	Gear Lever Y Sensor Circuit Intermittent Ckt
P0830	Clutch Position Switch A Circuit Malfunction
P0831	Clutch Position Switch A Circuit Low
P0832	Clutch Position Switch A Circuit High
P0833	Clutch Position Switch B Circuit Malfunction
P0834	Clutch Position Switch B Circuit Low
P0835	Clutch Position Switch B Circuit High
P0836	4 Wheel Drive Switch Circuit Malfunction
P0837	4 Wheel Drive Switch CKT Range/Perf
P0838	4 Wheel Drive Switch Circuit Low
P0839	4 Wheel Drive Switch Circuit High
P0840	Trans Fluid Press Sensor/Switch A Circuit Malfunction
P0841	Trans Fluid Press Sensor/Switch A CKT Range/Perf
P0842	Trans Fluid Press Sensor/Switch A Circuit Low
P0843	Trans Fluid Press Sensor/Switch A Circuit High
P0844	Trans Fluid Press Sensor/Switch A CKT Intermittent
P0845	Trans Fluid Press Sensor/Switch B Circuit Malfunction
P0846	Trans Fluid Press Sensor/Switch B CKT Range/Perf
P0847	Trans Fluid Press Sensor/Switch B Circuit Low
P0848	Trans Fluid Press Sensor/Switch B Circuit High
P0849	Trans Fluid Press Sensor/Switch B CKT Intermittent

4.6. P1000-P2000 Series: Engine and Transmission Issues

The P1000-P2000 series of codes covers a wide range of engine and transmission-related issues.

Mercedes Fault Code	Fault Code Meaning
P1000	Electronic Gear Selector Module: Defective N15/5
P1228	yet unknown code on 1997 C 220 CDI
P1386	knock control
P1570	Intermittant No-Start Immobiliser Module
P1747	Electronic Gear Selector Module: Defective Interaction of CAN with control unit A1(instrument cluster)
P1750	Electronic Gear Selector Module: Very low control unit supply voltage
P1832	Electronic Gear Selector Module: SHORT in circuit N15/5 output stage
P1910	Electronic Gear Selector Module: Control Unit over voltage
P1912	Electronic Gear Selector Module: Weak touch push button voltage
P2000	NOx Trap Efficiency Below Threshold (Bank 1)
P2001	NOx Trap Efficiency Below Threshold (Bank 2)
P2003	Particulate Trap Efficiency Below Threshold (Bank 1)
P2004	Particulate Trap Efficiency Below Threshold (Bank 2)
P2031	Exhaust Gas Temperature Sensor Circuit (Bank 1 Sensor 2)
P2032	Exhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 2)
P2033	Exhaust Gas Temperature Sensor Circuit High (Bank 1 Sensor 2)
P2080	Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 1)
P2081	Exhaust Gas Temperature Sensor Circuit intermittant (Bank 1 Sensor 1)
P2100	Throttle Actuator Control Motor Circuit/Open
P2101	Throttle Actuator Control Motor Circuit Range/Performance
P2208	transmission: The speed of Y3/6n2 to Y3/6n3 is excessive

4.7. B Codes: Body Control System

B codes relate to the body control system, which includes components such as airbags, central locking, and electric windows.

Mercedes Fault Code	Fault Code Meaning
B1000	HRA Headlamp range adjustment: Supply voltage of the control unit is too low (undervoltage)
B1004	LCP Lower Control Panel: Control unit does not match vehicle type
B1056	Automatic Air Conditioning: Problem in CAN communication with control unit DCM-RL
B1201	Electric seat adjustment front left: Hall sensor front height M27m3
B1213	If seat memory installed: ext right rearview mirror voltage faulty
B1214	If seat memory installed: ext right rearview mirror voltage faulty
B1226	In-car temperature sensor (B10/4)
B1227	Outside temperature indicator temp sensor (014)
B1128	Heater core temperature (B10/1)
B1229	Heater core temperature (B10/1)
B1230	Evaporator temperature sensor (B10/6)
B1231	ECT sensor (B11/4)
B1232	Refrigerant pressure sensor (B12)
B1233	Refrigerant temperature sensor (B12/1)
B1234	Sun sensor (B32)
B1235	Emissions sensor (B31)
B1241	Refrigerant Fill
B1246	PTS Parktronic: A42b1 (left outer sensor, front bumper) The plug connection has poor contact or is loose, or the sensor or cable is faulty
B1310	Left/Window airbag sensor is defective
B1315	Problem in Front passenger child seat recognition
B1416	Coolant circulation pump (M13)
B1417	Duovalve (Y21y1), left
B1418	Duovalve (Y21y2), right
B1419	Electromagnetic clutch (A9k1)
B1420	Idle speed increase
B1421	Pulse module (N05)
B1422	Series interface (K1) connection to instrument cluster (A1)
B1423	Switchover valve block (Y11)
B1424	Activated charcoal filler actuator (A32m2) open
B1425	Activated charcoal filler actuator (A32m2) closed
B1432	Non-USA DTC
B1459	Series interface (K2) connection to instrument cluster (A1)
B1462	Wide open throttle (WOT) position signal diesel engines
B1476	Airbag malfunction indicator and warning lamp is defective
B1481	HRA: Part E2m1 (Right headlamp range adjustment motor) has short to ground
B1489	HRA: Part E2m1 (Right headlamp range adjustment motor) has open or short to positive
B1492	HRA: Part E1m1 (Left headlamp range adjustement motor) has short to positive/td>
B1617	Part E19/1 (Left license plate lamp) is defective
B1618	Part E19/2 (Right license plate lamp) is defective
B1628	Part E2e5 (Turn signal lamp) in module E2 (Right front headlamp unit) is defective.
B1703	Intermittant No Start in AAM Immobiliser Module
B1729	PSE Pneumatic system doorlock Control Module A37
B1736	Navigation system’s CD Player: Check General CD, Check CD data block, Flimsy CD data
B1768	Faulty open data flap limit switch (0025) Front flap
B1773	HRA: Zero position programming has not yet been carried out or is not possible
B1850	Electric seat adjustment front right: CAN communication interrupted with DCMC1000 Traction System Control Module

4.8. C Codes: Chassis System

C codes refer to the chassis system, including ABS, ESP, and suspension-related issues.

Mercedes Fault Code	Fault Code Meaning
C1010	Battery Voltage Low
C1011	ASR/ETS/ESP Circuit Open or Shorted
C1012	Battery Voltage High
C1020	CAN Communication Fault
C1021	CAN Communication With EA/CC/ISC Control Module Interrupted
C1024	CAN Communication With Engine Control Module Interrupted
C1025	CAN Communication BAS communication with ESP control unit faulty
C1100	Left Front Axle VSS Circuit Fault
C1101	Right Front Axle VSS Circuit Fault
C1102	ETS/ASR, ABS Left Axle VSS Circuit Fault
C1103	Right Rear Axle VSS Circuit Fault
C1121	AIRmatic: fault in component B22/3 (level sensor)
C1122	AIRmatic: fault in component B22/4 (level sensor)
C1123	AIRmatic: fault in component B22/6 (level sensor)
C1132	AIRmatic: fault in component B22/8 (level sensor)
C1133	AIRmatic: fault in component B22/9 (level sensor)
C1135	AIRmatic: fault in component B22/3 (level sensor)
C1140	BAS light, play in steering column causes steering angle sensor to lose memory(?)
C1142	ABS Lateral Acceleration Sensor Open/Shorted
C1144	AIRmatic: fault in component B7 (pressure sensor)
C1200	Stop Light Switch Open/Shorted/Implausible
C1300	Left Front Axle Solenoid Valve (Hold) (A7/3y6) Open/Shorted
C1303	Right Front Axle Solenoid Valve (Hold) Open/Shorted
C1311	Switchover Solenoid Valve (Release) Open/Shorted
C1312	Master Cylinder Switchover Valve
C1401	High Pressure Return Pump Circuit Open/Shorted; Will Not Shut Off
C1501	SPS P-Valve
C1504	BAS light, play in steering column causes steering angle sensor to lose memory(?)