"SRS Malfunction, Service Required" Error – How to Deal with It?

It can be nerve-racking to spot the error message, "SRS Malfunction, Service Required", and have no clue what's wrong with your car. In this article, we'll look at why the error message may appear on the instrument panel to help you zero in on the correct diagnosis and how to deal with the issue. But first, let's have a look at what the SRM system is and its function. 

SRS malfunction message highlights

• Common reasons:one of the airbags requires service
• How to fix:take it in for inspection
• Possible consequences:safety system may not work properly
• Priority level:High
• Can you drive?Carefully
• DIY repair:Impossible
• Repair price range:$250-$550

The SRS System and Its Function

The Supplemental Restraint System is a safety feature common in Mercedes-Benz brands. SRS stands for Supplemental Restraint System. It's also referred to as the airbag system or passive restraint system. The system is designed to protect the driver and the car passengers from physical harm in the event of an accident. The system activates when it detects factors such as a car's speed above 25 mph followed by an abnormal deceleration. It also automatically detects braking and collision positions. 

When the system activates, it tightens the seat belt to restrict the car occupants from sudden forward movement. It also deploys the airbag to cushion the driver and other occupants from hitting the dashboard and steering wheel.

Some newer advanced versions of the SRS system have side airbags to protect the passengers from impact, with the side pillars and SRS curtains to offer protection from broken glass. Some even recline back the front seats to shield the passengers from spinal or neck injuries that may come about during the recoil phase of a collision. 

What does SRS Warning Light Mean?

Whenever there's an issue with the supplemental restraint system, a yellow warning light with the initials SRS usually appears on the dashboard. Some vehicles show the symbol of an airbag to indicate a malfunction of the SRS. You may also see the error message "SRS Malfunction Service Required "when the SRS malfunctions. 

The warning light usually illuminates when there's a problem with the airbag, seat belt, or any other SRS component that may prevent airbag deployment and the seat belt's tightening in case of a collision. After ignition, the warning light usually appears in the instrument cluster for a few seconds and then disappears. This is a self-test sequence to determine if the SRS system is in its right condition.

Whenever the SRS warning light fails to disappear after a few seconds, this is a sign that there's something wrong with the SRS. Some components of the supplemental restraint system are:

• Airbags.
• Seat belt pre-tensioners.
• Crash sensors.
• Airbag control unit.
• Front passenger seat occupancy sensor.
• Belt force limiters.

Can You Drive with the SRS Warning Light On?

The illumination of the SRS or airbag warning light on the dashboard may not be a concern since it doesn't affect drivability. However, the airbag system may fail when you need it the most, leading to costly or deadly repercussions.

That's why taking your car to a professional auto mechanic for proper diagnosis and repair is advisable as soon as you notice the SRS warning light on your car's instrument panel. If you're not able to take your car for fixing, ensure you drive extra carefully with awareness of potential hazards to prevent accidents. 

Causes of an SRS Malfunction

Some of the reasons for an SRS malfunction are:

1) Faulty Seat Occupancy Sensor

The seat occupancy sensor is a push button sensor that functions magnetically and is located under the seat cover and above the seat foam. Its push-fit clip mounting design helps signal if someone or something is on the seat. It also measures the weight of the seat's occupant. The warning light then comes on if the seat is occupied and the seat belt is not fastened. The seat belt occupancy sensor can turn faulty if 

• The car seat becomes wet due to rain or spilled liquid.
• If you place objects such as a laptop or a phone on the seat.
• If there are faulty wires and plugs connected to the sensors.

2) A Faulty or Broken Seat Belt Latch

The work of a seat belt latch is to firmly secure and properly position the occupants by allowing the seat belts to be fastened. It reduces the risk of injuries during clashes. If anything gets into the seat belt buckle, it may become faulty and not safely secure the passenger. 

3) A Damaged Steering Wheel Clock Spring

The steering wheel turns through the clock spring, a notable spiral wound rotary electrical connector that you can locate between the steering wheel and its column. It connects to the car's electrical system, the SRS computer, and the steering wheel airbag.

The clock spring also allows the beeping of the car horn and conveys signals from the steering buttons to the car computer. As a result of the constant movement of wire ribbons inside the clock spring, it's prone to wear and tear. Whenever the clock spring fails, the SRS or airbag light may appear on the instrument panel, especially when turning the steering wheel.

This may prevent the steering airbag from inflating in an accident. Another symptom of a damaged clock spring is the steering buttons failing to operate.

4) Faulty SRS Module

The SRS airbag module is an SRS component that determines when the airbag is deployed, communicates with the car engine, and stores crash impact data. It's also called the electronic airbag crash unit or the sensing diagnostic module (SDM). For most cars, you can locate it next to the driver's seat under the center console.

If the SRS airbag module becomes faulty, it cannot deploy the airbags in the car, making its occupants lose the protection needed in case of an accident. Water, heat, aging, and severe vibration can all damage the SRS module, making the airbag light appear on the dashboard. 

5) A Defective Airbag

Some of the airbags in Mercedes-Benz cars are front airbags, curtain airbags, side airbags, and knee airbags. The airbag is a bag that quickly inflates and deflates to prevent injuries to the vehicle's occupants by providing a cushion against the car's interior or external objects in case the car experiences a collision.

It works using a chemical reaction that releases nitrogen gas, inflating the airbag. A defective airbag fails to inflate during a collision or suddenly inflates when there's no collision. This poses the risk of a fatal injury; therefore, driving with a defective airbag is unsafe. 

6) Malfunctioned Crash Sensors

The crash sensors work is to detect a collision and send the signals to the SRS computer for an appropriate response, such as the deployment of airbags and seat belt restraint. They are also known as impact sensors. The impact sensor is positioned at the front of the car. The accelerating force is also part of the data sent to the control unit.

When the crash sensor malfunctions, it can also compromise other safety features, such as the airbag pressure switch that deploys the airbag during the impact of a collision. Acceleration and pressure sensors are also part of the safety system that triggers the deployment of airbags. 

How to Fix an SRS Malfunction

Depending on the diagnosis, one can fix an SRS malfunction making the" SRS Malfunction, Service Required" error message disappear. Some of the ways to fix the SRS malfunctions are:

• One of the remedies car owners use to solve the issue of a faulty seat occupancy sensor is driving around with a buckled seatbelt on an empty passenger seat to avoid the SRS warning light. But that's not a lasting solution. Replacing the sensor can also be difficult for most car owners. This leaves them with the option of bypassing the sensor using a seatbelt chime bypass device and seat occupancy sensor emulator. Bypassing the sensor sends false signals that the seat is occupied.
• A damaged clock spring needs replacing. Replacing it can be challenging since it requires removing the airbag assembly and the vehicle's steering wheel. It also needs special tools such as the steering wheel puller and skills to handle the replacement. This means the replacement needs experienced hands. After replacing the clock spring, the last step is resetting it to function properly.
• A faulty airbag needs replacement. If the airbag deploys in an accident it also needs replacing since you cannot reuse it. Replacing the airbag requires the removal of the entire airbag module, which requires a special set of skills. If replacing the faulty airbag is outside your DIY scope, it's best to leave the job to a professional.
• Repairing the SRS control module requires a high skill set since it's complicated. The best option to fix a malfunctioned SRS control module is to reset it. This involves removing the crash data and resetting the diagnostic trouble codes(DTC). The SRS control module is reprogrammable unless it's damaged by fire, floods, or brute force that damages its hardware components.
• Crash sensors, such as the front impact sensors, need replacement if they get damaged in an accident or have faulty wiring. Replacing the SRS impact sensors is easy and less time-consuming. Before replacing the sensor, you'll have to disconnect the negative cable from the battery's terminal to prevent electrocution. You'll then locate the sensor, mostly found at the front end. A user manual can also help locate the sensor. The final step should be removing the old sensor and installing a new one.
• If you find that the seat belt latch or the seat belt sensor is causing the error message, "SRS Malfunction, Service Required", after diagnosis, you'll have to replace them.
• After making the necessary repairs and replacements, the final step is to reset the SRS warning light or "SRS Malfunction, Service Required" error message. You can reset it by restarting your car and taking it for a test drive. If the warning light is still on, you can plug the seatbelt around a heavy item to trick the sensors that there's an occupant on the seat. Another way is to reset the DTC codes using an OBD II scanner.

Bottom Line

There you have it-the "SRS Malfunction, Service Required" error message and how to deal with it. If you're not in a position to diagnose and fix the issue, seek the services of a qualified technician.