Airbag control unit with part number 28501194

What is the function of Airbag Control Unit 28501194?

The airbag control unit with part number 28501194 is the central SRS module (Supplemental Restraint System) for the Audi A4 B9. It monitors and controls the vehicle’s entire airbag system, processes sensor signals, and is responsible for deploying the restraint systems in the event of a crash.

As the brain of the safety system, it continuously collects data from various crash sensors distributed throughout the vehicle. Based on this information, the control unit decides within milliseconds whether and which airbags (e.g., passenger airbag, seat airbag) or belt tensioners need to be deployed to provide optimal protection for occupants.

An additional critical function is storing crash data. After deployment, the module locks its internal memory and prevents further use until this data is professionally reset. This ensures safety and guarantees that the system is thoroughly inspected after an accident.

Why does Airbag Control Unit 28501194 fail?

The most common cause of failure for control unit 28501194 is the storage of crash data following an accident, which results in a system lockout. In addition, internal electronic faults—such as defective memory chips or issues with sensor processing—can also lead to module failure.

After an airbag deployment, so‑called crash data is stored in the control unit. These data permanently block the module’s functionality, indicated by a lit SRS warning light. This condition is intentionally designed by the manufacturer and cannot be cleared using standard diagnostic tools.

Independently of accidents, purely electronic defects may also occur. Internal errors in memory or the processor can trigger error codes such as “B1111: Control unit defective” or “Component defective.” Such faults are often due to aging components or faulty solder joints, requiring component‑level repairs.

How do you recognize a defect in Control Unit 28501194?

A defect in control unit 28501194 primarily manifests as a constantly illuminated airbag warning light (SRS lamp) in the instrument cluster. Additionally, specific fault codes in the fault memory cannot be cleared, and communication problems with diagnostic equipment may arise.

The clearest symptom is the persistently lit airbag warning light. It does not turn off after starting the vehicle, indicating a serious fault embedded in the system. This condition signals that the airbag system is not operational.

During a workshop diagnosis, fault codes that cannot be erased are read out. Typical entries include “internal error,” “side‑impact sensor error,” or the general code for a defective control unit. Attempts to clear the memory fail because the fault is persistent.

In some cases, the control unit becomes inaccessible to diagnostic tools. No communication occurs between the tester and the SRS module, suggesting a complete failure of the internal electronics.

In which vehicles is part number 28501194 installed?

The airbag control unit with part number 28501194 is specifically designed for models of the Audi A4 series. It is mainly used in the B9 generation and its facelift variant, produced over a broad manufacturing period.

At Airbag24, we repair part number 28501194 for the following models:

Audi A4 B9 8W (2015–2019) Audi A4 B9 8W Facelift (2019–2024)

Is repairing Control Unit 28501194 worthwhile?

Yes, repair is an economically and technically sensible alternative to costly replacement. Not only do you save significantly, but you also get your original part back, eliminating the need for time‑consuming re‑coding of the vehicle and restoring full functionality.

The cost savings are substantial. While a new part from the manufacturer can range from €400 to over €2,000, professional repair typically costs only a fraction of that amount. This often allows you to save more than 70% of the expense.

A key technical advantage is retaining the original part. Since the vehicle‑specific coding remains intact, the repaired control unit can simply be reinstalled (plug-and-play). By contrast, with used or new units, expensive and time‑consuming reprogramming at a specialized workshop is often required.

Furthermore, you receive 2 years’ statutory liability for defects on the completed repair, something generally unavailable when purchasing used parts from a reseller.

How is Control Unit 28501194 professionally repaired?

After you send the removed control unit to Airbag24, it undergoes a standardized repair process. This includes an initial inspection, erasure of crash data, electronic component-level repairs, and a final functional test before reshipment.

Before removal, we recommend having the fault memory read out at a specialized workshop. Please include the diagnostic report with your shipment to provide our technicians with valuable information about the defect. The control unit is typically located in the center console and should be removed with the battery disconnected.

At Airbag24, the device is first opened and thoroughly analyzed. Stored crash data is then completely erased using specialized programming tools, restoring the module to its factory settings. If an electronic fault is detected, defective components such as memory chips or processors are identified and replaced.

Following successful repair, the control unit is resealed and ready for reinstallation. No new coding is required. After installation, simply clear the vehicle’s fault memory; the airbag warning light should then turn off.