Mercedes-Benz Check Engine Codes: Your Ultimate Guide

Mercedes-benz Check Engine Codes can be a source of frustration for owners and technicians alike. This comprehensive guide, brought to you by AutoExplain.com, dives deep into the world of Mercedes-Benz diagnostic trouble codes (DTCs), providing detailed explanations, potential causes, and effective solutions to get your Mercedes back on the road. Let AutoExplain.com assist you in swiftly resolving any warning lights that may appear.

1. Understanding Mercedes-Benz Check Engine Codes

Modern Mercedes-Benz vehicles are equipped with sophisticated onboard computer systems that constantly monitor various parameters and systems. When a deviation from the norm is detected, the system generates a Mercedes-Benz check engine code, also known as a Diagnostic Trouble Code (DTC). These codes are designed to help technicians diagnose and repair issues efficiently. These error codes will trigger a dash light. AutoExplain.com can help you decipher these codes and understand the underlying problems.

alt: Mercedes-Benz engine compartment showcasing advanced technology and monitoring systems.

2. Decoding Common Mercedes-Benz Error Messages

A Mercedes-Benz check engine code is a standardized alphanumeric identifier that corresponds to a specific fault or malfunction within the vehicle’s systems. These codes are read using a diagnostic scan tool connected to the vehicle’s OBD-II port. Here’s how to interpret them:

• First Character: Indicates the system affected:
  • P: Powertrain (engine, transmission)
  • B: Body (airbags, central locking)
  • C: Chassis (ABS, suspension)
  • U: Network Communication
• Second Character: Specifies whether the code is generic (0) or manufacturer-specific (1).
• Third Character: Denotes the subsystem:
  • 1: Fuel and air metering
  • 2: Fuel and air metering (injector circuit)
  • 3: Ignition system or misfire
  • 4: Auxiliary emission controls
  • 5: Vehicle speed control and idle control system
  • 6: Computer output circuit
  • 7: Transmission
  • 8: Transmission
• Fourth and Fifth Characters: Provide a specific fault identification number.

3. Common Mercedes-Benz Check Engine Codes and Their Meanings

Here’s a breakdown of some common Mercedes-Benz check engine codes, their potential causes, and possible solutions. When troubleshooting, remember to consult AutoExplain.com for expert assistance.

3.1. Mercedes Fault Code P261F71

Feature	Description
Fault Code Meaning	The output for circulation pump has a malfunction. Actuator is blocked.
Known Problem Of	Mercedes Sprinter Vans
Likely Causes	Coolant intrusion into the vacuum system via the water pump.
What’s Happening?	On model OM651 4 Cylinder Diesel Engine the coolant water pump is vacuum actuated. The internal seal in the waterpump gives way and allows coolant (antifreeze) to enter the vacuum system. The vacuum system operates with the engine running. As the vehicle is driven the vacuum is so powerful it pulls coolant (antifreeze) deeper into the vacuum system causing havoc on the entire vacuum system.
Possible Symptoms	Check Engine Light, Little to no acceleration, Coolant leak, Brake Pedal Pressure issues, Engine overheating
Parts Potentially Requiring Replacement	Water Pump, Coolant, Seals, Tubes, Hoses, Vacuum Actuators, Vacuum Pump
Affected Systems	Engine, Cooling System, Vacuum System, Turbocharging, Brake System
Severity	Can be very severe if left unfixed Repair requires MASTER LEVEL Technician and not something for the DIYer

3.2. Mercedes Fault Code P126A00 – OM642 Engine oil cooler leak

Feature	Description
Fault Code Meaning:	Intake Port Shutoff Actuator is faulty.
Known Problem Of:	Mercedes Sprinter Vans
Likely Causes:	Failure of component: intake manifolds, or the intake manifold actuator motor.
What’s Happening?:	Over time (several thousand miles) 50-100k miles the inside of the intake manifolds get clogged with EGR soot, buildup causing the intake swirl flaps to stick. The sticking or binding of these flaps then binds the motor which causes the check engine light and or a sever loss of acceleration.
Possible Symptoms You May Experience
Parts That Could Need Replacement:
System(s) Affected:	– Engine
Severity:	Can be very severe if left unfixed Repair requires MASTER LEVEL Technician and not something for the DIYer

3.3. P0400 Series: Exhaust Gas Recirculation (EGR) System

These Mercedes-Benz check engine codes relate to the Exhaust Gas Recirculation (EGR) system, which is designed to reduce emissions by recirculating a portion of the exhaust gas back into the engine’s intake manifold.

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

Possible Causes:

• Defective EGR valve
• Blocked or restricted EGR passages
• Faulty EGR pressure sensor
• Vacuum leaks in the EGR system
• Electrical issues (wiring, connectors)

Troubleshooting Steps:

1. Inspect the EGR valve for carbon buildup and proper operation.
2. Check the EGR passages for any blockages.
3. Test the EGR pressure sensor using a multimeter.
4. Look for vacuum leaks in the EGR system.
5. Examine the electrical connections and wiring for damage.

alt: Detailed view of an EGR valve, highlighting potential areas for carbon buildup and malfunction.

3.4. P0500 Series: Vehicle Speed Sensor (VSS)

These Mercedes-Benz check engine codes are related to the Vehicle Speed Sensor (VSS), which provides information about the vehicle’s speed to the engine control unit (ECU) and other systems.

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

Possible Causes:

• Defective vehicle speed sensor
• Wiring issues (damaged, corroded, or loose connections)
• Faulty ABS module
• Incorrect tire size
• Damaged speedometer

Troubleshooting Steps:

1. Inspect the VSS for damage and proper installation.
2. Check the wiring and connectors for continuity and proper voltage.
3. Use a scan tool to monitor the VSS signal while driving.
4. Verify the tire size matches the vehicle’s specifications.
5. Test the ABS module for proper function.

3.5. P0600 Series: Control Module Issues

These Mercedes-Benz check engine codes indicate problems within the vehicle’s control modules, such as the engine control module (ECM) or transmission control module (TCM).

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

Possible Causes:

• Internal control module failure
• Programming errors
• Wiring or connection issues
• Power supply problems

Troubleshooting Steps:

1. Check the control module’s power and ground connections.
2. Inspect the wiring and connectors for damage.
3. Try reprogramming the control module.
4. Replace the control module if necessary.

alt: Location of an Engine Control Unit (ECU) in a vehicle, emphasizing its role in managing engine functions.

3.6. P0700 Series: Transmission Issues

These Mercedes-Benz check engine codes signal problems within the transmission system, covering a wide range of issues from sensor malfunctions to mechanical failures.

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

Possible Causes:

• Low or contaminated transmission fluid
• Faulty shift solenoids
• Defective transmission speed sensors
• Torque converter problems
• Internal mechanical damage

Troubleshooting Steps:

1. Check the transmission fluid level and condition.
2. Test the shift solenoids for proper function.
3. Inspect the transmission speed sensors.
4. Perform a transmission flush and filter replacement.
5. Consult a transmission specialist for internal repairs.

3.7. P0800 Series: Transmission Control System (TCS)

These Mercedes-Benz check engine codes relate to the Transmission Control System (TCS), which manages various functions such as gear shifting and torque converter lockup.

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

Possible Causes:

• Faulty clutch position sensor
• Wiring issues
• Solenoid malfunctions
• Hydraulic problems

Troubleshooting Steps:

1. Inspect the clutch position sensor and its wiring.
2. Test the solenoids for proper operation.
3. Check the hydraulic system for leaks and proper pressure.

3.8. P1000-P2000 Series: Engine and Transmission Specific Codes

This range of Mercedes-Benz check engine codes covers more specific engine and transmission issues, often related to fuel delivery, emissions, or internal component failures.

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

Possible Causes:

• Faulty sensors (oxygen, mass airflow, crankshaft)
• Fuel injector problems
• Ignition system issues
• Catalytic converter failure
• Transmission solenoid issues

Troubleshooting Steps:

1. Use a scan tool to gather more specific information about the code.
2. Test the relevant sensors and components.
3. Check for vacuum leaks and exhaust leaks.
4. Inspect the fuel system for proper pressure and flow.
5. Consult a repair manual or database for specific troubleshooting procedures.

3.9. B-Codes: Body Control System

These Mercedes-Benz check engine codes relate to the vehicle’s body control system, which includes various components such as airbags, lighting, and power 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

Possible Causes:

• Faulty sensors (e.g., airbag sensors, temperature sensors)
• Wiring issues (shorts, open circuits)
• Actuator failures (e.g., door lock actuators)
• Control module problems

Troubleshooting Steps:

1. Use a diagnostic scan tool to pinpoint the specific component or circuit causing the issue.
2. Inspect wiring harnesses and connectors for damage or corrosion.
3. Test sensors and actuators for proper function.
4. Check the relevant fuses and relays.

3.10. C-Codes: Chassis Control System

These Mercedes-Benz check engine codes pertain to the chassis control system, which includes the anti-lock braking system (ABS), electronic stability program (ESP), and suspension system.

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(?)
C1512	Brakes Overheated
C1600	Temperature After Engine Is Turned OffU0001 High Speed CAN Communication Bus

Possible Causes:

• Wheel speed sensor failures
• Brake pressure sensor issues
• Steering angle sensor malfunctions
• Hydraulic pump problems
• Suspension component failures (e.g., air struts, level sensors)

Troubleshooting Steps:

1. Inspect wheel speed sensors for damage and proper installation.
2. Check brake fluid level and condition.
3. Calibrate the steering angle sensor.
4. Test the hydraulic pump and solenoids.
5. Examine suspension components for leaks or damage.

3.11. U-Codes: Network Communication

These Mercedes-Benz check engine codes indicate communication problems between different control modules within the vehicle’s network.

Mercedes Fault Code	Fault Code Meaning
U0002	High Speed CAN Communication Bus Performance
U0003	High Speed CAN Communication Bus (+) open
U0004	High Speed CAN Communication Bus (+) low
U0005	High Speed CAN Communication Bus (+) high
U0006	High Speed CAN Communication Bus (-) open
U0007	High Speed CAN Communication Bus (-) low
U0008	High Speed CAN Communication Bus (-) high
U0009	High Speed CAN Communication Bus (-) shorted to Bus (+)
U0010	Medium Speed CAN Communication Bus
U0011	Medium Speed CAN Communication Bus Performance
U0012	Medium Speed CAN Communication Bus (+) open
U0013	Medium Speed CAN Communication Bus (+)