Audi A4 B7 8H Convertible airbag control unit repair

What is an Audi A4 B7 8H Convertible airbag control unit?

In the Audi A4 B7 8H Convertible, the airbag control unit acts as the central control unit of the restraint system (SRS). It evaluates what the crash sensors report and, in an impact, decides within milliseconds which airbags and seatbelt pretensioners fire.

From the moment the vehicle starts, the unit is permanently on duty: it continuously monitors the connected components and shows any detected fault via the airbag warning light. If an accident occurs, it stores the crash data and locks itself.

This control unit is fitted in the model series 2006 to 2009.

Why is the Audi A4 B7 8H Convertible airbag control unit defective?

Most often the cause is crash data that remained in the unit after an accident, even if no airbag was deployed. Other causes are aged electronic components, cold solder joints, corrosion and moisture at connectors, and voltage spikes.

This data record cannot be removed with an ordinary diagnostic tool. That applies even if your Audi looks undamaged from the outside. Regardless of any accident, the electronics wear over time, and solder joints can develop fine cracks.

A weak battery or jump-starting can briefly put excess voltage into the vehicle electrical system. If moisture gets into the connectors, corrosion can attack the contacts and cause malfunctions.

Signs of a defect are an airbag warning light that stays on, a fault memory that cannot be cleared, or a diagnostic tool that cannot establish contact with the control unit.

Common error codes for Audi A4 B7 8H Convertible airbag control unit repair

The codes that occur in the Audi A4 B7 8H Convertible point to the squib circuits of the front and side airbags, to the power supply, or to an internal fault in the unit. The respective code tells you which part of the system is affected.

A squib circuit code concerns the wiring including the airbag module, a supply code the power feed, and an internal code the control unit itself. The following messages are known:

• 00588 → Fault in the driver airbag squib circuit
• 65535 → Internal fault in the airbag control unit
• 00532 → Supply voltage too low, intermittent
• 00590 → Fault in the front passenger airbag squib circuit
• 01217 → Resistance fault, driver-side side airbag
• 01218 → Resistance fault, passenger-side side airbag

The way to clarify the problem is through the fault memory. A workshop or your own diagnostic tool reads out the codes. That the control unit is defective does not necessarily follow from this, because connectors, wiring or an airbag module are equally possible. Only the inspection shows where the cause lies.

What part numbers are available for the Audi A4 B7 8H Convertible airbag control unit repair?

On the label of your control unit you will find the part number, which defines the exact version. Within a model series, different numbers exist depending on equipment and year of manufacture, so you should take a look at the label before sending the unit in.

We know the following numbers for this model; the list is not complete.

• 8H0959655H

Compare the number on your unit with this list. This only ensures that you have the right unit in front of you. Whether it is defective only becomes clear by reading out the fault memory or through the inspection at Airbag24.

The procedure: first have the fault memory read out, disconnect the battery and remove the control unit. Then create a repair order online and send the unit to us. Inspecting, repairing and testing usually take 3–4 working days at Airbag24, after which you will receive your own unit back.

The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.