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How to Fix an Inoperable SOS Function in a Mercedes C-Class

When it comes to a vehicle’s safety features, not many brands come close to what Mercedes – Benz has to offer. Even the smaller Mercedes C-Class models are in a league of their own.

Although that is the case, it’s hard to silence the inner voice that keeps on repeating:

 “What if I get in an accident and no one is around?” 

“What if I don’t have enough time to call the emergency services for help?” 

Such jarring thoughts can plague anybody’s mind, and as such, they used to be a grave concern in the yester years, but modern cars have a workaround for such concerns.

Behold the SOS function! Many modern vehicles have this feature, and it is extremely helpful too as it cures your wayward thoughts. Nowadays, if you get into an accident, the SOS function immediately informs the authorities of your whereabouts. As such, help gets to you quickly, and the day is saved. All thanks to modern safety advancements.   

Perhaps, that is why our client Mr T bought his 2018 Mercedes C-Class CD220. The SOS feature worked fine in his vehicle except for one small issue. The warning sign on the dash showed that the feature was ‘inoperable’.  Interestingly, the warning sign was visible at the time of purchase as quoted by the client.   

Puzzled and worried about the predicament Mr T went to a garage, but they were unable to find or solve the issue. Finally, after much deliberation, he drove his Mercedes all the way from Tamworth and put his trust in Fitch Autos. 

Needless to say, our expert technician Matt got to work immediately.    

Fault Discovery 

On initial diagnosis, Matt found something puzzling. The diagnostic tool turned up fault codes P06530 and P06531. These codes are normally associated with the errors ‘VIN not present’ or “VIN not programmed’. But the car had no problem regarding VIN programming. On the contrary, it came in with an error message related to the SOS function! 

Why then did such fault codes present themselves in the scan? Could it be that the two things are connected? 

They could have been connected to each other. Perhaps, the ECU not recognizing the Vehicle Identification Number (VIN) led the SOS function to not work properly. After all, in the event of an accident, for the authorities to locate you, the car should have a registered VIN. Without it, the SOS function could be showing a malfunction. 

However, our technician thought about all the possibilities, including the one above before embarking on his research.   

To find out more, Matt decided to dig deeper. He had the basic idea of what was going on, but getting to the bottom of it all was necessary to complete this repair. Keep in mind that other technicians may have given up at this point or guessed at what the issue was, and perhaps that is what happened at the previous garage. But our expert, Matt, was insistent as he favoured moving on with the diagnosis rather than stopping in his tracks.  

Our very own Fitch Autos technician started the 15-step diagnostic procedure on the CD220. It is a streamlined process designed to make diagnosis more efficient and effective.  Not only did it save Mr T’s time and minimized the costs for him, the procedure made life easier for Matt as well. 

Moving Towards a Solution

During the 15-step diagnostic procedure, Matt found and identified the fault codes, using an industry-standard diagnostic tool. However, after countless tries, he couldn’t find anything related to the malfunction. Each time, the unusual codes presented themselves, and Matt hit a dead end. But something like that doesn’t stop the technicians at Fitch Autos, instead, it motivates them further.

So, next up, Matt tested the onboard system’s data to see if the buttons were registering any input. It all worked fine, and the control module was receiving the signals. Even a thorough visual inspection didn’t turn up anything unusual. 

So, to get to the bottom of this, our experienced technician consulted the Technical Service Information document provided by Mercedes. On deeper inspection of the manual, it became clear that the issue lay in the car’s software. 

In other words, there was never any problem with the VIN or the SOS function, but all of the troubles were the result of simple software corruption. It is something that takes only a few hours to solve once you know where the issue is. 

Interestingly, the technician at the other garage gave up before even reaching this point. However, Matt made it through thanks to his determination, quick thinking, and use of the 15-step diagnostic procedure.   

The Solution for the Malfunction 

After identifying the root cause of the issue, Matt turned his attention to updating the software. He used the Xentry Mercedes dealer software to pinpoint the problem and then install the upgraded Mercedes – Benz software version. 

The installation took a few hours to complete.

Fortunately, Mr T came to Fitch Autos where our technician diagnosed and fixed the SOS malfunction issue all in a day. The client came in and went home with his Mercedes C-Class on the same day. What a relief for the guy who drove from Tamworth just to see us.

Satisfaction for our Clients Guaranteed 

Mr T was extremely disappointed after showing his car to the first garage. The people there could not diagnose the problem, let alone find a solution. 

Luckily, the second time worked like a charm as he came to Fitch Autos to get a second diagnosis for his Mercedes. Our technician put him at ease and went to work on the solution. 

Matt’s presence of mind and commitment to delivering a fix led him to look through the Mercedes service manual. Not many technicians take this route, but Matt is unlike any other technician. He is always focused on delivering a solution, regardless of how he gets to the finish line.

So, it was there, in the Mercedes resource document that he found out that the SOS function issue is quite rare. Most importantly, he discovered that they are usually caused by corrupt software.    

So, the update was done and the fault codes were rechecked. Unsurprisingly, nothing new turned up and Mr T’s frustration turned into joy.

Once again, if it wasn’t for our technician Matt and the values we instill in all the employees at Fitch Autos, we would never have succeeded. We pride ourselves on providing satisfaction to all our clients. Their happiness after we finish a repair is what drives us to do better every day.

If you want award-worthy service for your Mercedes, don’t hesitate to call us at 01543 401257.

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