Mercedes-Benz automobiles are among the most cutting-edge on the market. Mercedes’ onboard computers constantly monitor hundreds of separate systems, sensors, and variables, adjusting safety, and other vehicle parameters as needed to keep everything running smoothly. Basically, this means that if anything goes wrong with your car, your car will be on top of it by coming up with fault codes.
Warning lights (such as “Check Engine,” “Brake,” and “Temperature”) illuminate when fault codes are present in your Mercedes, but this is usually insufficient for the average Mercedes owner to determine the root of the problem.
In this guide, I’ll explain what fault codes are in more detail, how to get fault codes on a scanner, and what the most common fault codes are for Mercedes cars. So, whenever you’re ready, just scroll down and begin.
What Is a Fault Code?
In the past, if anything went wrong with your car, a trained mechanic would rely almost entirely on guesswork to resolve the problem. This was a painstakingly long process that involved taking components apart, testing them individually, and putting them back together before testing another possibly faulty part. Nowadays, mechanics use scanners that plug into a modern vehicle to get fault code readings.
A fault code is a series of letters and numbers that describe a very particular problem in a car. They also go by the name Diagnostic Trouble Codes (DTCs) or On-Board Diagnostic II (ODB-II).
Fault codes differ from ordinary malfunction indicator lamps or MILs (engine temperature, battery warning, oil pressure, brakes, etc.) by being more precise. The MILs simply inform the driver that something’s wrong under the hood or inside, whereas fault codes can tell an informed user of what the precise problem is.
Deciphering DTCs
Each DTC will contain 5 characters with at least 1 letter, with the first character always being a letter.
1st character
There are 4 characters that will show up in the beginning—P, C, B, and U.
- P refers to powertrain problems, which cover engine, transmission, and any associated parts.
- C refers to chassis problems, including steering, suspension, and braking functions.
- B refers to body problems, which will cover almost every part of the passenger area.
- U refers to network and vehicle integration problems, which are mainly derived from the onboard computer.
2nd character
There are only 2 codes here—0 and 1.
- 0 is the SAE code, a.k.a. a generic or global code.
- 1 is the manufacturer’s code, a.k.a. enhanced code.
3rd character
This code ranges from 0 to 7.
- 0 refers to fuel and air controls.
- 1 refers to fuel and air metering.
- 2 refers to fuel and air metering, along with the injector circuit.
- 3 refers to the ignition system, including misfires.
- 4 refers to auxiliary emissions controls.
- 5 refers to speed control, idle control system, and aux inputs.
- 6 refers to the computer and output circuitry.
- 7 refers to the transmission.
In addition, there may be A, B, or C codes in the 3rd character’s spot. These letters refer specifically to hybrid propulsion systems.
4th and 5th characters
The final numbers refer to a specific component related to a faulty system. You will see what examples of these characters mean in another section.
Hot to Get DTC Codes
Before doing anything, you first need to pick up a DTC scanner, such as the Bosch ADS 625 Model 3920. After receiving the scanner, now you need to figure out how to get the DTC readings from your car.
- Locate the 16-pin connector in your car. Most Mercedes will have them somewhere underneath the dash. If you’re struggling to locate the connector, open up the owner’s manual and follow the diagram.
- Plug the DTC scanner into the 16-pin connector.
- Turn on your car following the DTC scanner’s instructions. For some models, you only to turn your car on to the accessory position, which is the 2nd position when you turn the key in the ignition. For push-button ignition systems, simply press the button without hitting the brake pedal.
- Turn on the DTC scanner and navigate to the “Read Codes” section (depending on the scanner model). If the scanner isn’t specifically built for Mercedes cars, you will need to input your car’s info (make and model).
- Let the DTC scanner run until the screen shows error codes.
Now, it’s important to note that a DTC scanner does not fix your car. It simply identifies the problem, which you can convey to your mechanic (who will probably run another DTC test, just to be sure).
Mercedes Fault Codes List
With the basic information regarding DTCs out of the way, it’s time to look at a few examples. The following list is incomplete as it only shows some of the most common DTCs that will appear on your screen. If you’re getting a reading outside of what shows on the scanner’s display, I recommend getting your car checked out by a professional mechanic.
| DTC | 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 |
| 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 |
| 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 |
| 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 Malfunction |
| 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 |
| 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 Disconnect 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 |
| P1000 | Electronic Gear Selector Module: Defective N15/5 |
| P1228 | yet unknown code on 1997 C 220 CDI |
| P1386 | knock control |
| P1570 | Intermittent No-Start Immobilizer 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 |
| 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 |
