Many drivers are currently seeing the ‘Emergency call system not available’ or ‘SOS call system failure’ error message on the dashboard of their BMW.

BMW’s telematics module has two power feeds, one from the vehicles main power supply, the other from it’s own backup battery. This means in the event of a serious accident (even with complete power loss) the SOS function can still be used. The Telematic Communication Box (TCB) monitors the emergency battery via an internal self-test after each start-up procedure. The emergency battery does have a limited service life. If the capacity of the emergency battery is exhausted to the extent that placing an emergency call can no longer be guaranteed then this is shown by a Check Control message (Emergency call system fault or SOS call system failure). A fault entry is also stored in the Telematic Communication Box.

SOS Call System Failure – Telematics Battery Replacement

A good majority of the time the ‘Emergency call system not available’ or ‘SOS call system failure’ error is a consequence of the telematics emergency call battery deteriorating over time and not providing a significant output to keep the emergency call system powered in the event of power loss. This is simply down to battery degradation of the backup battery over time.

This issue is very quickly becoming a hot topic in the BMW world as because it is just a battery degradation issue, BMW will not cover this fault outside of their 2 year warranty as they put it down to ‘wear and tear’. Although these batteries are rechargeable, once they reach a lower peak performance they cannot be recovered and a replacement will be required. The batteries overall life will be greatly reduced in colder climates, that is why we see a huge uptake of cars requiring battery replacement during the winter months.

The fault codes that usually accompany a failed battery are:

  • B7F341 Emergency battery: Hardware faulty.
  • B7F343 Emergency battery: Charge interval reached.

Many BMW dealers are quoting astronomical figures to rectify this fault, usually in the region of £600 from a autherised BMW main agent as they state it requires a huge amount of labour as it usually is housed in the roof of the vehicle.

At Grosvenor we have made the decision to standardise the charge for telematics battery replacements across the whole BMW range at £195 inc VAT. This includes the replacement battery, labour and clearing the fault down once the replacement has been completed.

There are of course other reasons as to why you may get this ‘SOS call system failure’ error message such as module faults, water damage etc. We will always confirm that the battery is indeed the issue before replacement. This issue affects all BMW’s manufactured after 2014 right up to current production.