Mercedes-Benz 190 W201 airbag control unit repair

What is a Mercedes-Benz 190 W201 airbag control unit?

In the Mercedes-Benz 190 W201, the airbag control unit is the central control unit of the restraint system (SRS). It evaluates what the crash sensors report and, in an accident, decides within milliseconds which airbags and seatbelt pretensioners are triggered. After an accident it stores crash data and locks itself.

In the background, the unit continuously checks all components of the restraint system, from the sensor to the squib circuit. If it detects an irregularity, it draws attention to it with the airbag warning light.

The unit is fitted in the Mercedes-Benz 190 W201 (1982 to 1993). It was manufactured by Bosch. Which version is in your vehicle depends on equipment and year of manufacture.

Airbag24 inspects, repairs and tests your unit. You get your own control unit back, not a different one.

Why is the Mercedes-Benz 190 W201 airbag control unit defective?

Most often the cause is crash data stored after an accident, even if no airbag was triggered; an ordinary diagnostic tool cannot delete it. Ageing components, cold solder joints, moisture with corrosion on connectors or voltage spikes are also possible causes.

You can usually recognise the problem by three things: the airbag warning light stays on permanently, the fault memory refuses to be cleared, or the diagnostic tool cannot establish contact with the control unit.

Electronic components wear out over the years, and a cold solder joint is not visible from the outside but can interrupt the current path. Moisture attacks connectors in the airbag circuit, so that signals are distorted or missing altogether. A weak battery or a jump start can produce voltage spikes that put stress on sensitive circuits. At first, such faults often occur only intermittently and only become permanent over time.

Common error codes for Mercedes-Benz 190 W201 airbag control unit repair

The codes for the Mercedes-Benz 190 W201 point to internal control unit faults, communication problems, supply voltage that is too high or too low, interrupted squib circuits or stored crash data.

The following codes are known:

• B1000 → Airbag control unit malfunction
• B2500 → Internal control unit fault
• B1561 → Crash data stored in the control unit
• U0151 → Communication with the airbag control unit lost
• B1315 → Control unit supply voltage too low
• B1318 → Control unit supply voltage too high
• B1420 → Open circuit in the driver airbag squib circuit
• B1421 → Open circuit in the passenger airbag squib circuit

You can read out the fault memory with a diagnostic tool. The appearance of a code does not yet prove a defect in the control unit; an airbag module, a connector or a wire can just as well be to blame. Only an inspection brings clarity.

If the system reports an interruption in a squib circuit, the cause does not necessarily lie in the unit itself. The wiring to the module or the module itself can also be responsible, which is why a single entry never decides the repair on its own.

What part numbers are available for the Mercedes-Benz 190 W201 airbag control unit repair?

On the label of your control unit you will find the part number, which determines the exact version. Because the numbers vary with equipment and year of manufacture, checking the label is the surest way to the right unit.

We know of these part numbers, though the list is not complete:

• 0048201910 (Bosch)
• 0048202410
• 0285001060 (Bosch)

Compare the number on your unit with the list. This only ensures that it is the right unit; whether it is defective only becomes clear from reading out the fault memory or from our inspection.

The route to repair: first have the fault memory read out and disconnect the battery, then remove the control unit. Next, create a repair order online and send the unit to us. Inspecting, repairing and testing usually take 3–4 working days at Airbag24.

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.