What does a "Service Brake - Visit Workshop" message mean?
Depending on your driving habits, your brake pads may last a couple of weeks or months before the brake pads are completely worn out and metal on metal contact is reached, which significantly reduces braking distance and can be dangerous.
Besides the usual worn pads and rotors, this message may also indicate a problem with the SBC braking system, which Mercedes-Benz used in the early 2000s on models such as the E-Class and CLK-Class.SBC is short for Sensotronic Brake Control, which is an advanced electro-hydraulic system that improves stopping performance.
Unlike traditional brake system setups, this system has no physical link between the brake pedal and the hydraulics that operate the brakes. It is also known as brake-by-wire. Instead, a computer controls their activation and gives the vehicle a certain degree of autonomy. This allows the vehicle to adjust braking power to current road conditions, which ensures the best possible braking performance at any given moment.
The heart of the system is the SBC module, which incorporates the functions of the ABS pump and brake booster into one unit. It uses an electric pump that pressurizes brake fluid, which is then stored in a reservoir beneath it. There are also a series of valves, which distribute and control the brake fluid pressure for each wheel while braking. This system relies on a range of sensors to understand vehicles’ behavior on the road and drivers’ intentions.
Given the complexity of this system and its safety-critical nature, even the slightest irregularity will offset its operation. Depending on the failure causing the issue and its severity, this can even affect the braking performance.
If that happens, that ‘Brake-visit workshop’ warning message will alert the driver. As an additional safety measure, this system has a traditional brake master cylinder that acts as a fail-safe device. Still, its performance is limited, and braking power may be reduced, as it has no brake booster.
I replaced the brakes but still got a ‘Service brake - Visit Workshop’ warning
Some drivers will assume that the ‘Service brake - visit workshop’ message only warns them about worn brakes on their Mercedes-Benz. Although this is one possibility, replacing brake pads and rotors on the front may not solve the issue.
If the service brake warning message still comes up, the rear brake pads may need to be replaced as well.
Another possible issue is that the brake pad wear sensor was not replaced or connected properly.
As obvious as it sounds, the problem can be within the SBC system itself, and tracking it down requires a suitable diagnostic tool.
What may cause Service Brake - Visit Workshop warning to pop up?
The Brake system in modern Mercedes-Benz cars is complex and elaborate, and any potential malfunction can affect braking and therefore should be taken seriously. There are several common fault points owners should check first, especially on vehicles with SBC systems.
- Pads and rotors - are wear-and-tear items and will trigger this warning light when they become too thin. Besides this, a damaged or faulty wear sensor, which gives false readings, may cause the same thing. In both cases, a visual inspection and analysis of stored error codes will reveal more.
- Brake pad wear sensor - old sensor was reused, is not connected properly, or was not replaced.
- The brake light switch - is a sensor above the brake pedal itself, which tells the vehicle when the driver is pressing it. Simple as it may be, this device's internal components can eventually wear out, causing it to send incorrect signals. The brake light switch is an inexpensive component, and replacing it is a simple job.
- Sensotronic Brake Control - system requires a steady current flow, as any voltage drop or spike may cause it to malfunction. To prevent this from happening, Mercedes-Benz has fitted their cars with an auxiliary battery that powers up the SBC module. With time, this battery may wear out and needs to be replaced with a new one. However, this can be an issue, as many owners are not even aware of its existence.
- The SBC module - itself is quite prone to failures, with the electric pump being the most common issue here. It is possible to rebuild a malfunctioning module, although this delicate job is best done by an experienced specialist.
- Dead or weak battery - Yes a weak battery can trigger this warning. Charge the battery and the error should reset if the problem was due to low voltage.
How long do brakes last on a Mercedes-Benz?
Brake pads and rotors on any car are components whose life-cycle is not predetermined because it is significantly impacted by driving habits.
We have seen Mercedes-Benz that needed new brake pads replaced every 15,000 miles (you know who you are) and others where brake pads lasted over 50,000 miles. On average, Mercedes-Benz brake pads last between 30,000 and 40,000 miles.
Brake pad lifespan and their duration will depend on several factors, including:
- driving style
- brake pad material/quality
- highway or city driving
- vehicle use
All Mercedes-Benz cars nowadays have wear indicators, sensors that measure how thick brake pads and rotors are. When they become too thin, the vehicle will warn the driver with that ‘Service brake’ message.
In addition to usual brake wear, owners whose cars use the SBC system must know it counts every braking. The idea is that the SBC module has a certain service life, during which it can activate a certain number of times.
Once that threshold number is exceeded, owners should replace the whole module. Depending on running conditions and driving habits, this may happen at mileages that range anywhere between 300,000 and 600,000 miles.
How to reset service brake warning on a Mercedes-Benz?
After diagnosing the cause of the issue and replacing faulty components, it is still necessary to reset the ‘Service brake’ message. One way to do this is by using a diagnostic tool that can access the brake or SBC module. The only exception is SBC modules that exceeded their threshold number, which is a value that cannot be reversed.
As we have explained, there are two reasons why that ‘Service brake - Visit Workshop’ message keeps popping up in your Mercedes-Benz.
The first one is worn brake pads and rotors or faulty wear sensors that are sending incorrect signals. Another likely cause is the SBC brake system itself in those vehicles that have it.
The cause of the issue here may be anything from a worn brake pedal switch to a faulty SBC module.