Airbag control unit with part number 3C0 909 605 E

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

The airbag control unit 3C0 909 605 E controls the restraint system (SRS) in Volkswagen. It evaluates the crash sensor signals and determines in an accident within milliseconds which airbags and seatbelt pretensioners are triggered.

At the same time it monitors the entire system and shows faults via the airbag warning light in the instrument cluster.

After an accident the unit stores crash data and locks itself.

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

A failure can come from crash data stored after an accident, even without a triggered airbag. A standard diagnostic tool does not delete this data.

Aged electronic components can also cause the failure. Over time, components lose reliability, and this shows up in the behaviour of the system.

Cold solder joints on the circuit board, as well as moisture or corrosion at plug connections, are also typical causes.

Voltage spikes also affect the electronics, for example with a weak battery or after a jump start.

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

The defect shows up at the airbag warning light, a fault message in the instrument cluster, a missing connection to the diagnostic tool, or a fault memory that cannot be cleared. With such a finding, airbags and seatbelt pretensioners may possibly not deploy in an emergency.

The signs at a glance:

• airbag warning light, permanently or intermittently
• fault message in the instrument cluster
• no connection to the diagnostic tool
• fault memory that cannot be cleared

If the light goes out after a drive, a check is still worthwhile.

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

The 3C0 909 605 E is fitted in these vehicles: Volkswagen Passat B6 3C (2005-2010).

The following lists the vehicles for this part number:

• Volkswagen Passat B6 3C (2005-2010)

Read out the fault memory before removing the unit, and then compare the part number on the label of the control unit with this page, to check whether the unit is defective or a cable is causing the fault.

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 E work?

Before removal, read out the fault memory and enclose the log. Then disconnect the battery, remove the control unit and create the repair order online before sending it in well packed. Airbag24 checks the unit, replaces defective components, deletes the crash data and runs a function test; processing usually takes 3–4 working days.

Afterwards your own unit goes back to you.

The stated working days refer only to checking, repairing and testing.

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 E get to Airbag24?

You send the control unit 3C0 909 605 E to Airbag24 as a parcel or opt for a UPS collection for an extra charge. The return after the repair follows by UPS.

Place the printed repair order in the parcel and pad the unit so that it withstands knocks well.