Peugeot 405 Break I Facelift airbag control unit repair

What is a Peugeot 405 Break I Facelift airbag control unit?

In the Peugeot 405 Break I Facelift, the airbag control unit is the nerve centre of the restraint system (SRS). It continuously evaluates what the crash sensors report and, in an accident, triggers exactly the right airbags and seatbelt pretensioners within milliseconds. At the same time it monitors the entire system and indicates faults with the airbag warning light.

The unit is fitted in the Peugeot 405 Break I Facelift (1992 to 1996). The control unit is made by Autoliv.

A self-test runs every time the engine is started, and sensors, squib circuits and the power supply are also checked while driving. If the unit detects a fault, the warning light comes on in the instrument cluster. After an accident it stores crash data and locks itself.

Why is the Peugeot 405 Break I Facelift airbag control unit defective?

If the airbag warning light in the Peugeot 405 Break I Facelift stays on permanently, the most common cause is crash data stored after an accident, even if no airbag was triggered. Other possible causes are aged electronic components, cold solder joints, moisture with corrosion on connectors and voltage spikes, for example with a weak battery or after a jump start.

Usually the first thing you notice is the warning light that no longer goes out. If you then try to clear the fault memory, the message returns or clearing does not work at all. Sometimes the diagnostic tool cannot even connect to the control unit.

Behind these signs there is often an accident in the past: the stored crash data cannot be removed with an ordinary diagnostic tool, and a repair is needed. Without an accident, the cause is more likely gradual change. Components on the circuit board age, solder joints lose contact, moisture attacks the connectors, or a voltage spike damages the electronics.

Common error codes for Peugeot 405 Break I Facelift airbag control unit repair

In the Peugeot 405 Break I Facelift, the stored codes point to internal faults of the control unit, to problems with the supply voltage, to interrupted communication or to faults in the squib circuits. Which code is in the memory depends on the particular fault pattern.

The following codes are documented for this vehicle:

• B1000 → Internal fault, hardware defect or locked crash data
• B1001 → Internal control unit fault, airbags disabled
• B1004 → Internal fault of the airbag control unit
• U0151 → Communication with the airbag control unit lost
• 9650 → Supply voltage fault
• A601 → Squib circuit driver airbag, first stage: short to positive
• A603 → Squib circuit passenger airbag, first stage: short to positive

Error codes are read out with a diagnostic tool. A code alone does not necessarily mean the control unit is defective, because connectors, wiring or an airbag module can just as well be the cause. Only the inspection shows which part is affected.

What part numbers are available for the Peugeot 405 Break I Facelift airbag control unit repair?

You will find the part number on the label of the Peugeot 405 Break I Facelift airbag control unit. It determines the exact version, because depending on equipment and year of manufacture there are several numbers within one model series.

The following numbers are known for this vehicle, although the list need not be complete:

• 96 385 925 80 (Autoliv)

Compare the number on your unit with this list. The comparison only shows whether it is the right unit. Whether there is a defect is only clarified by reading out the fault memory or by the inspection in our workshop.

The path to repair looks like this: first read out the fault memory, then disconnect the battery and remove the control unit. Afterwards, create a repair order online and send the unit to Airbag24. Checking, repairing and testing there usually take 3–4 working days. 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.