BMW will not drive or charge after an accident?

SME is the BMW high-voltage battery management control unit. In practical workshop language it is often treated as the battery BMS, but this article uses the name SME because that is how owners, technicians and service centers commonly refer to it.

In an electric vehicle, the SME contains the control board, high-voltage contactors and two internal pyrotechnic disconnects. The control board manages battery operation and commands the contactors to close once the system confirms that the vehicle is in a safe state.

After a crash, a crash event is stored in the control board memory. The internal pyrotechnic disconnects operate at the same time. The SME then stops commanding the contactors to close again, so the high-voltage system is not activated and the vehicle does not become ready to drive.

The problem most commonly appears as one or more of the following:

• the BMW powers on but will not drive;
• drive cannot be engaged;
• the hybrid will not start the powertrain;
• the vehicle will not charge;
• the vehicle is still not ready to drive after SME replacement;
• faults are cleared but return immediately.

On some vehicles, drive readiness may be indicated by READY in the instrument cluster. Many owners do not notice or recognize this indicator, so the article uses clearer terms such as ready to drive, drive activation and charging availability.

Diagnostics are required whether the original SME will be restored or replaced with a new unit.

During the first remote connection, BIMFIX checks:

• whether a crash event is actually stored in the SME;
• which software level is installed in the vehicle;
• whether the SME and other high-voltage control units communicate correctly;
• the general condition of the battery;
• whether there are faults involving temperature sensors, battery modules, insulation or other components;
• whether other faults would still prevent vehicle activation after the SME is restored or replaced.

For this reason, the SME should not be removed first and diagnosed later. The vehicle-specific data required for the work must be saved before the original unit is removed.

The SME used in a BMW electric vehicle differs from the hybrid version both physically and in software. The repair paths are therefore different.

BMW electric vehicles

The EV SME has a serviceable construction and may be physically repaired and software-restored if the installed software level allows it.

BMW hybrids

The hybrid SME has a metal housing that is not designed for normal disassembly. It cannot be physically repaired or software-restored and must be replaced with a new unit.

A hybrid BMW requires a new SME. Used SME units are not installed in hybrid vehicles.

BMW electric vehicles

• BMW 5 Series G60 Sedan
• BMW 5 Series G68 Sedan
• BMW 5 Series G61 Touring
• BMW 7 Series G70
• BMW i3L G28 BEV Sedan
• BMW i4 G26 Gran Coupé
• BMW iX I20
• BMW X1 U11
• BMW X1L U12
• BMW X2 U10
• BMW iX3 G08 BEV LCI
• MINI Countryman U25

BMW hybrids

• BMW 2 Series U06 Active Tourer
• BMW 5 Series G60 Sedan
• BMW 5 Series G90 M5
• BMW 5 Series G61 Touring
• BMW 5 Series G99 M5 Touring
• BMW 7 Series G70
• BMW X1 U11
• BMW X3 G45
• BMW X5 G05 LCI
• BMW XM G09

Restoration for the newer SME generation is under development and is not currently included in this service.

The original SME in an electric vehicle can be restored if the vehicle has not yet received software level 25-11.

Starting with software level 25-11 inclusive, bench programming access is blocked. The SME no longer responds to the programmer, so restoration of the original unit is no longer possible.

In that case, a new SME is installed. A customer may also choose a new unit even when the original SME is still technically restorable.

1. Initial remote diagnostics. The crash event, battery condition, related faults and software level are checked.
2. Saving vehicle-specific data. The required data is read from the original SME before removal. It is tied to the individual vehicle and its control unit.
3. Battery and SME removal. BMW factory removal and installation instructions can be provided when required.
4. Physical and software restoration. The SME is disassembled, the two internal pyrotechnic disconnects are replaced, and the control unit is restored and prepared for pairing back to the vehicle.
5. Reassembly and sealing. The control unit is reassembled and sealed by BIMFIX.
6. Third pyrotechnic disconnect. A new disconnect for the front plastic high-voltage module is supplied together with the restored SME. The customer installs it separately.
7. Final remote connection. After installation, the SME is programmed, coded, paired, commissioned and the battery cell identifiers are recorded.
8. Final functional check. The complete vehicle is scanned again and forward movement, reverse movement, drive activation and charging are checked.

BIMFIX manages the complete procedure from the first diagnostic session through the final vehicle check. Another technician cannot simply complete the last step because they do not have the saved vehicle-specific data.

EV SME restoration is provided as a complete package for the battery-side work required after a crash event:

• initial vehicle diagnostics;
• saving the original SME’s vehicle-specific data;
• software restoration of the control unit;
• replacement of the two internal pyrotechnic disconnects;
• SME reassembly and sealing;
• the third pyrotechnic disconnect for the front high-voltage module;
• final programming, coding, pairing and commissioning;
• a complete rescan and a basic driving and charging check.

If physical faults remain in other systems, the customer receives recommendations for the required repair. A separate follow-up connection can be arranged after those repairs are completed.

A new SME is installed in two main situations:

• the customer chooses a new control unit;
• the original SME is not restorable, including vehicles updated to software level 25-11 or newer.

A new EV SME is supplied factory-sealed and already contains two new genuine BMW internal pyrotechnic disconnects. The third front disconnect must still be replaced separately.

When a new SME is installed, the vehicle-specific data required to restore the old unit does not need to be read. Initial diagnostics are still mandatory because other faults may prevent successful vehicle activation after replacement.

After installation, the new control unit is programmed, coded, paired and commissioned, the battery element data is recorded, and the vehicle is functionally checked.

A used EV SME requires software preparation before installation, and it remains a compromise solution.

A prepared clean software state is written to the control unit before it is programmed and paired to the vehicle. However, the original vehicle-specific data from the original SME cannot be recreated for the used unit. As a result, informational faults related to certificates or data readiness may remain.

A used SME is not installed in a hybrid BMW. Hybrids require a new control unit.

The procedure is not entirely remote because the SME must be physically removed and shipped to BIMFIX.

A substantial part of the work is nevertheless completed remotely:

• initial diagnostics;
• battery condition and related fault checks;
• saving vehicle-specific data;
• software-level verification;
• final SME programming, coding and commissioning;
• a complete vehicle rescan and functional check.

The remote connection requires a Windows laptop, an ENET cable, a stable internet connection and TeamViewer. Mobile data is also acceptable when the connection is stable. The 12-volt battery must be charged, and a stable battery support unit is recommended during programming.

The job does not end when the SME reports successful commissioning.

During the final check, the customer:

• powers on the vehicle;
• checks drive activation;
• moves the vehicle a short distance forward and backward;
• connects the vehicle to a charger and confirms that charging begins.

At the same time, BIMFIX scans every control unit again, reviews any remaining faults and performs straightforward service or software procedures directly related to completing the SME work.

Complex additional work—such as programming new radar sensors, pairing headlamps, using paid coding files or coding other vehicle systems—is carried out only after separate approval from the customer.

To assess the situation more quickly, provide:

• the vehicle VIN;
• model and model year;
• whether the vehicle is electric or hybrid;
• what was damaged in the accident;
• whether the restraint or safety system deployed;
• whether the battery or SME has already been removed;
• whether another SME has been installed;
• whether the vehicle powers on, engages drive and charges;
• which repairs or programming work have already been performed.

A remote session is then arranged and the complete diagnostic check is performed.