Airbag control unit with part number 3C0 909 605 H

What does the airbag control unit 3C0 909 605 H do?

The airbag control unit 3C0 909 605 H is the central control unit of the restraint system (SRS) at Volkswagen. It processes the signals from the crash sensors and decides in an accident which airbags and seatbelt pretensioners are triggered.

The decision is made within milliseconds. Between accidents, the unit monitors the entire system and reports faults via the airbag warning light.

After an accident, it stores crash data and locks itself.

Why does the control unit 3C0 909 605 H fail?

Stored crash data is the most common cause, even when no airbag was triggered. This data cannot be deleted with a standard diagnostic tool. Other causes are aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

An accident without airbag deployment can still leave data behind. Airbag24 deletes it during the repair.

The other causes are rather gradual. Electronic components age, solder joints can stay cold, and moisture attacks the plug connections.

How can you tell that the 3C0 909 605 H is defective?

The airbag warning light in the instrument cluster stays on permanently or intermittently, and an error message appears. In addition, there is no connection to the diagnostic tool and a fault memory that cannot be cleared, both signs of a fault in the 3C0 909 605 H.

The signs at a glance:

• Airbag warning light on permanently or intermittently
• Error message in the instrument cluster
• No connection between the diagnostic tool and the control unit
• Fault memory cannot be cleared

Airbags and seatbelt pretensioners may not deploy in an emergency for as long as the fault persists.

Which vehicles is the 3C0 909 605 H fitted in?

The airbag control unit 3C0 909 605 H is fitted in vehicles from Volkswagen. It is fitted in these vehicles: Volkswagen Passat B6 3C (2005-2010).

The models are listed here:

• Volkswagen Passat B6 3C (2005-2010)

Compare the part number on the label of the removed unit with this page. That only ensures that it is the right unit. Also have the fault memory read out beforehand, because only the log shows whether the control unit is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 3C0 909 605 F, 3C0 909 605J, 3C0 909 605M, 3C0909065F, 3C0909605K, 3C0909605N.

How does the repair of the 3C0 909 605 H work?

First read out the fault memory and attach the log, then disconnect the battery; only after that is the 3C0 909 605 H removed. Processing at Airbag24 usually takes 3–4 working days.

Next, create the repair order online and send in the unit, well packed.

Airbag24 checks the unit on the test bench, replaces defective components, deletes stored crash data and carries out a function test. Afterwards, your own unit goes back to you.

Our repairs come with 2 years' statutory liability for defects. 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.

How does the control unit 3C0 909 605 H get to Airbag24?

You send the control unit 3C0 909 605 H as a parcel, or book a UPS collection for an extra charge. After the repair, Airbag24 returns it by UPS.

Place the printed repair order in the parcel and pack the unit so that it is shock-resistant.