Airbag control unit with part number 6N4T-14B056-AB

What is the function of the Airbag Control Unit 6N4T-14B056-AB?

The Airbag Control Unit 6N4T-14B056-AB is the central control module of the Occupant Restraint System (SRS) in the Ford Focus II (Mk2). It processes signals from crash sensors, deploys airbags and seatbelt pretensioners in the event of a collision, and stores relevant crash data. A malfunction typically results in a permanently illuminated airbag warning light.

As the heart of the safety system, this control unit is responsible for monitoring and controlling all pyrotechnic and electronic components. It continuously analyzes data from acceleration sensors to activate the appropriate restraint systems within milliseconds in the event of a collision.

In addition, it logs all system-relevant faults and irrevocably stores crash data after an activation event. This data retention is a safety feature that mandates a post-crash system check and often necessitates repair.

Why does the 6N4T-14B056-AB control unit fail?

The most common cause of failure for the 6N4T-14B056-AB control unit is the storage of crash data following an accident. Other causes include internal electronic defects, which manifest as fault codes such as B1342, as well as moisture damage. These defects are usually hardware-related and require professional electronic repair.

After a collision—even if only a knee airbag deploys—the unit writes a so‑called hardcode into its memory. This record locks the control unit and cannot be erased using conventional diagnostic tools. The airbag warning light remains on permanently, making repair unavoidable.

Another common issue is an internal defect on the circuit board. This often appears as fault code B1342—“SRS control module.” Such errors indicate defective components or faulty solder joints, preventing the control unit from communicating with the vehicle.

It’s important not to confuse this control unit with similar part numbers from other Ford models. While part numbers 6N4T-14B321-AA and 8M5T-14B321-BE are also used in the Ford Focus II, avoid mixing them up with parts from the Ford Transit, such as 6C1T-14B056-AE, as these are incompatible.

How do you recognize a defect in the 6N4T-14B056-AB?

A defect in the 6N4T-14B056-AB control unit primarily manifests as a permanently illuminated airbag warning light on the instrument cluster. Often, the control unit becomes inaccessible to diagnostic tools, preventing fault diagnosis or clearing error codes via the OBD2 interface.

The clearest sign is the airbag warning light that fails to turn off after the engine starts. This indicates a serious, safety‑critical fault in the restraint system requiring immediate inspection.

Another typical symptom is complete communication failure. Workshops find they can no longer access the airbag control unit with their diagnostic equipment. The system is thus locked and cannot be read or reset.

In some cases, the vehicle display also shows a text message like “Refer to manual,” alerting the driver to a problem with the safety system and recommending a manual check.

In which vehicles is the 6N4T-14B056-AB control unit installed?

The airbag control unit with part number 6N4T-14B056-AB was specifically developed by Ford for the second-generation Ford Focus (Mk2, internal designation DA3). It is found in models from model years 2004 to 2007, including facelift versions.

At Airbag24, we professionally repair the 6N4T-14B056-AB control unit for the following models:

Ford Focus 2 (model years 2004–2007)

Ford Focus 2 Facelift (model years 2004–2007)

How does repair work at Airbag24?

Repair at Airbag24 follows a standardized process aimed at restoring full functionality. After submitting the removed unit, stored crash data is cleared, defective electronic components are replaced, and the device is reprogrammed. All repairs include a final test and 2 years' statutory liability for defects.

First, a qualified workshop should read out the fault memory to confirm that the issue truly lies within the control unit. Following proper removal, the unit is securely packaged and sent to Airbag24 along with the completed repair order.

Upon receipt, our technicians perform an initial inspection. Restoration involves expertly erasing crash data and replacing any defective electronic components on the circuit board. Finally, original functionality is fully reinstated.

After successful repair and a thorough final inspection, the control unit will be shipped back to you. Once installed, it is typically ready to use immediately (plug-and-play). Of course, you receive 2 years' statutory liability for defects on the completed repair.