Mercedes-Benz SRS Malfunction: Airbag Light Troubleshooting

Is the SRS or airbag warning light on in your Mercedes-Benz instrument cluster? Are you getting the warning message: Restraint System Defect! SRS Visit Workshop! Two of the main reasons why the SRS malfunction comes on are a dead battery or SOS TeleAid system problems. Keep on reading to understand how to troubleshoot and reset the SRS light.

How to Reset the Mercedes SRS Light with the UCAN-II Pro

Use the UCAN-II Pro to read SRS fault codes and clear stored codes after the underlying problem has been repaired. A current fault must be repaired before the code will stay cleared. Stored codes can usually be erased after the fault is no longer present. Codes showing as CURRENT mean you must fix the problem before clearing the code.

1. Connect the scanner to the OBD-II port under the driver’s dashboard.
2. Turn on the scanner.
3. Select Diagnostics
4. Select AutoScan VIN or manually select the vehicle model.
5. Select Control Units
6. Select Body
7. Select Airbag or SRS (Supplemental Control System)
8. Select Read Codes. Make sure all your codes are STORED in status. Any codes with CURRENT status need to be fixed to change to STORED.
9. Select ERASE at the bottom of the screen.

Note that if the vehicle has been in a crash and has deployed an airbag, it may need the module replaced. After an airbag deployment, the deployed airbags and activated seat belt tensioners must be replaced. Inspect the sensors, wiring, and connectors. The SRS control module may require replacement or model-specific programming according to Mercedes service information.

What Does the SRS Light Mean?

SRS stands for Supplemental Restraint System. If this warning light stays on in your Mercedes-Benz, that means that there is a problem with the airbags or the components that are part of the SRS system. It is very unlikely that your airbags will deploy randomly, but the concern is that they may not deploy at all in the case of an accident. The vehicle may still operate, but the restraint system may not provide full protection. Diagnose the warning immediately and follow the model’s owner’s manual.

Under normal operation, when you first turn the ignition and start the car, the light stays on for about 5 seconds and then turns off. If the SRS light stays on constantly or you get a Restraint System Defective, Visit Workshop’ warning, or airbag light, you know you have a problem.

SRS Warning System 

The SRS system checks the operation of several components in your car, such as:

• Airbags
• Airbag control unit
• Crash sensors
• Emergency Tensioning Devices
• Belt force limiters
• Child occupancy sensor in the front passenger seat.

These systems and other sensor data are checked when the driver turns on the ignition. If all these systems check out okay, the SRS light goes out. The SRS components are also checked frequently when the car is running. If a malfunction is detected, the SRS warning lamp or error message is displayed in the instrument cluster.

How to Read and Reset the SRS Airbag Light

Unfortunately, the SRS  Airbag light doesn’t reset on its own. Even if the problem has been addressed, you need an Airbag scanner to reset the light. Very often, the light goes on because of a dying battery. But once the light is on, it will stay on even when you install a new battery until you manually reset it.

A basic OBD-II reader only accesses generic engine and emissions codes. Mercedes SRS faults require a full system scanner that can communicate with the restraint control module. You will need a more advanced scan tool to reset the airbag light. You can get your airbag reset tool for around $110-150, which is how much diagnosis costs anyway. The fault code identifies the affected circuit or system so you can continue testing before replacing parts.

Our favorite scanner for reading and resetting your SRS/airbag light is the YOUCANIC full system scanner, which reads SRS and engine fault codes. If you need a scanner that will also troubleshoot Transmission, ESP, ABS, and any other control unit on your Mercedes-Benz, check out the YOUCANIC full system scanner, a powerful diagnostic scanner for Mercedes-Benz cars.

It reads the SRS light (Airbag Control Unit) and every control unit in your Mercedes-Benz. However, Many older Mercedes models use the round 38-pin diagnostic connector for access to systems beyond generic OBD-II. Verify scanner and adapter coverage for the exact model before purchasing; these require a 38-pin connection unless you purchase the 38-pin to OBD2 adapter.

If you maintain more than one vehicle, you should consider getting the YOUCANIC scanner, which covers more vehicles, not just Mercedes-Benz. It allows you to read and diagnose control systems in most cars. It supports active tests, resets, and special functions on compatible vehicles and streams sensor data live. It’s what independent auto repair shops use and is easy to use.

Common Causes of an SRS or Airbag Warning

Are you wondering what the problem could be with your car? Why is the SRS warning staying on? Here is a list of some of the most common problems with the SRS system on a Mercedes-Benz.

• Seat Occupancy Sensor in the passenger seat.
• Low battery voltage or a charging system fault.
• Seat belt latch.
• Steering Wheel Clock Spring
• Seat Belt Sensor
• Damaged wiring or connectors in the doors or under the seats.
• Defective Airbag
• Damaged impact sensor, wiring, or connector.

 

• When the SRS warning is on, one or more airbags or seat belt tensioners may activate unintentionally or may not deploy as intended during a crash.
• Airbags contain perchlorate material that requires special handling.
• Airbags and Emergency Tensioning Devices (ETD) are designed to function only once. Once these systems deploy, they must NOT be reused.
• Before disconnecting an SRS component, switch off the ignition, disconnect the battery according to the model-specific procedure, and wait the specified discharge time. Never probe an airbag igniter circuit with a test light or standard ohmmeter.
• Do not use seat covers unless approved by Mercedes-Benz. Seat covers can restrict the proper operation of the airbags integrated into the seats.
• If you are involved in an accident and the airbags are deployed, a small amount of powder will be released from the airbag. Avoid breathing the powder in the airbags as it could cause breathing difficulties.
• Airbag deployment depends on crash severity, direction, deceleration, seat occupancy, and the restraint system’s control logic.
• Be careful when working on the doors, as sensors and airbags are in this area. If you damage any of these components, the SRS system may show a warning and not protect you adequately in an accident.