Customer complaint
An SOS warning that remained after battery replacement
This Volkswagen Golf Mk8 was presented with an emergency-call system fault. The instrument cluster displayed an SOS warning instructing the driver to visit a workshop.
Before MPH Northwest became involved, the SOS backup battery had already been replaced in an attempt to resolve the issue. The warning remained and the system continued to report a fault.
Initial assessment
Confirming the condition of the SOS system
On arrival at the vehicle, we confirmed that the SOS warning was active on the instrument cluster and that the SOS status LED was illuminated red.
This was an important part of the initial assessment. The system was still operating sufficiently to report its own status, so further diagnosis was required before condemning the complete emergency-call control unit.
OEM diagnostics
ODIS identified a control-module fault
We connected ODIS, Volkswagen Group's OEM diagnostic software, and carried out a diagnostic assessment of the emergency-call system.
The SOS control unit contained fault code B200049, described as "Control module faulty".
A fault code is not automatically a parts list
Although the fault description suggested an internal control-unit problem, replacing the complete SOS module without further investigation could have resulted in an unnecessary and considerably more expensive repair.
Technical investigation
Volkswagen information identified the actual fault
As an independent Volkswagen Group specialist, MPH Northwest has access to manufacturer technical information in addition to OEM diagnostic equipment.
We located the relevant Volkswagen technical information for this fault condition. The manufacturer guidance confirmed that the SOS control unit itself did not necessarily require replacement.
The known issue was associated with the emergency-call system's backup antenna.
Repair
Replacing the backup antenna with a genuine repair kit
Following the Volkswagen repair procedure, the SOS unit was removed and the backup antenna fault was repaired using the genuine Volkswagen repair kit.
Once the repair kit had been installed, the SOS control unit was reassembled and refitted to the vehicle.
Commissioning
Adapting the SOS unit after the physical repair
Refitting the repaired unit was only part of the process. ODIS was then used to carry out the required adaptation and commissioning procedure for the emergency-call system.
The stored B200049 fault was successfully cleared and the SOS system was checked again to confirm correct operation.
Final result
The emergency-call system restored to operation
Following the repair and adaptation, the SOS system returned online and the emergency-call warning was resolved.
During the final system checks we also confirmed that the vehicle had outstanding remote software updates available.
Most importantly, the Golf was repaired without unnecessarily replacing the complete SOS control module.