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Error code reference

Bosch Dryer Error Code E:110

COM module (HomeConnect)

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COM module (HomeConnect) - D-Bus version protocol mismatch.

First step from the service manual

Issue eFSB to DLCB; try reflashing the UIM module.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E:110 means on a Bosch dryer

The E:110 error code on a Bosch dryer indicates a communication failure within the HomeConnect smart home module, specifically a D-Bus version protocol mismatch. D-Bus is an inter-process communication system used to pass messages between software components. In this context, it facilitates communication between the COM module (the HomeConnect connectivity board) and other control systems in the dryer. When the firmware versions on these modules are misaligned, the D-Bus protocol versions they expect to use no longer match, and communication breaks down entirely, triggering E:110.

The two primary components involved are the COM module (HomeConnect board) and the DLCB (Download Control Board), which interfaces with the UIM (User Interface Module). The diagnostic process begins by issuing an eFSB (electronic Firmware Service Bundle) command to the DLCB, which attempts to synchronize or update the firmware environment. If the protocol mismatch persists after that step, the next action is to reflash the UIM module to bring its firmware in line with the rest of the system.

This error is almost always a software-layer issue rather than a hardware failure. It commonly surfaces after an incomplete or interrupted over-the-air firmware update, a failed HomeConnect app-initiated update, or a module replacement where the replacement part carries a different firmware version than the rest of the control system. Physical hardware faults are a secondary consideration and should only be investigated after firmware remediation steps have been exhausted.

Source: manufacturer service documentation.

Common causes of E:110

  1. 01

    Incomplete or interrupted firmware update

    Wiring / connection

    If a HomeConnect app-initiated or remote firmware update was interrupted by a power loss or network dropout, individual modules can be left on mismatched firmware versions. Check the HomeConnect app for pending or failed update notifications.

  2. 02

    UIM module firmware out of sync

    Wiring / connection

    The User Interface Module may be running a firmware version that no longer matches the D-Bus protocol version expected by the COM module. Reflashing the UIM module is the recommended corrective step.

  3. 03

    Replacement module with mismatched firmware

    Wiring / connection

    If the COM module, UIM, or DLCB was recently replaced, the new part may have shipped with a different firmware version than the rest of the control system. The eFSB process issued to the DLCB is designed to address this.

  4. 04

    Corrupted COM module firmware

    Part replacement

    Internal corruption of the HomeConnect module's firmware can cause it to report an incorrect D-Bus protocol version. This may require a full firmware reload or module replacement if reflashing does not resolve the mismatch.

  5. 05

    Faulty COM module (HomeConnect board)

    Part replacement

    If firmware remediation steps including the eFSB command and UIM reflash fail to clear E:110, the COM module itself may have a hardware fault preventing it from operating on the correct protocol version. Replacement of the board would then be necessary.

See the test procedure for each cause

Frequently asked questions about E:110

What does E:110 mean on a Bosch dryer?
E:110 indicates a D-Bus version protocol mismatch involving the COM module, which is the HomeConnect smart connectivity board. The COM module and another internal control module are running firmware that uses incompatible communication protocol versions. This prevents the modules from exchanging data correctly. The error is a software-layer issue and is addressed by issuing an eFSB update to the DLCB and, if needed, reflashing the UIM module.
Will resetting my Bosch dryer clear the E:110 error?
A basic power reset is unlikely to permanently clear E:110 because the underlying cause is a firmware version mismatch between internal modules. The mismatch will persist across power cycles until the firmware is synchronized. A proper fix requires issuing an eFSB command to the DLCB or reflashing the UIM module through a service procedure.
Can I still use my dryer safely when E:110 is displayed?
The E:110 error specifically targets the HomeConnect communication module and does not directly affect the core drying functions of the appliance. In many cases the dryer may still operate for standard cycles. However, any smart home or remote control features tied to the HomeConnect system will not function reliably until the error is resolved. Consult a qualified technician if you are uncertain about operation.
How do I fix the E:110 error on a Bosch dryer?
The repair process starts with issuing an eFSB (electronic Firmware Service Bundle) command to the DLCB to attempt a firmware environment synchronization. If E:110 persists after that step, the UIM module needs to be reflashed with current firmware. These procedures typically require a service technician with access to Bosch diagnostic tools. If reflashing does not resolve the mismatch, the COM module or UIM module may need to be replaced.
How much does it cost to repair a Bosch dryer showing E:110?
If the issue is resolved through a firmware reflash alone, repair costs are primarily the labor charge for a service call, which typically ranges from around $80 to $150 depending on your location. If a component such as the COM module or UIM module requires replacement, total repair costs including parts and labor can range from $150 to $400 or more depending on parts pricing and local labor rates.

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