B1625 airbag control unit fault

What does error code B1625 mean?

Error code B1625 indicates a critical malfunction in the side airbag sensor system. Typically, this fault is logged when the control unit detects a fault in the side‑collision sensor assembly on either the left (LH) or right (RH) side of the vehicle. Depending on the manufacturer, the code may also point to short circuits or other circuit faults.

The exact definition of the code varies. Common variants include B1625 for the left side‑collision sensor and B1625/22 for the right sensor. In some vehicle models, the code may alternatively indicate a “lamp keypad output error.”

From a technical standpoint, the airbag control unit continuously monitors the electrical circuits of the sensors. If an implausible value, a short circuit, a wire break, or an internal sensor fault is detected, B1625 is stored in the fault memory and the airbag warning light illuminates. For example, on Toyota and Scion vehicles, code B1625 specifically refers to the left side‑airbag sensor circuit.

What symptoms are associated with B1625?

The most obvious symptom of error code B1625 is a permanently illuminated airbag warning light in the instrument cluster. This indicates that a safety‑related fault exists in the restraint system, potentially preventing the side airbags from deploying correctly—or at all—in the event of a crash.

The warning light remains on after the engine starts and does not extinguish as usual. This is a clear sign that the system’s self‑diagnostic has detected a fault and recorded it in memory.

In addition to the warning light, depending on the vehicle model, a text message may appear on the onboard computer display indicating a problem with the airbag system. During a workshop diagnosis, error code B1625 can be retrieved from the control unit’s fault memory.

What causes error code B1625?

The primary causes of B1625 are diverse, ranging from defective side‑collision sensors and internal electronic faults within the control unit itself to issues with the wiring harness. Common culprits include broken wires, short circuits in the sensor circuitry, or poor electrical connections due to corrosion or moisture.

Electronic malfunctions are a frequent source of errors. These include faulty side‑airbag sensors, a defective Body Control Module (BCM), or an internal fault on the airbag control unit’s circuit board.

Wiring and connection problems represent another major category of causes. This includes frayed or damaged cables, corroded connectors, or open circuits between the sensors and the central control unit.

Environmental factors can also trigger the fault. Water ingress into the control unit or connector assemblies may lead to short circuits, while constant vibrations and mechanical stress over time can cause material fatigue and contact issues.

Which vehicles are affected by B1625?

Error code B1625 is manufacturer‑independent and occurs across various brands. It is particularly well‑known in models from Toyota, Skoda, Mitsubishi, as well as Mercedes‑Benz and Volkswagen. The specific configuration of sensors and control units varies depending on the vehicle series.

At Airbag24, error code B1625 is professionally repaired for a wide range of vehicles. Specific models include:

Skoda: Octavia RS Mk3

Mitsubishi: L200 K70

Toyota: Corolla Wagon, Estima XR50 (model years 2006–2019)

Scion: Various models equipped with side‑airbag systems

Mercedes‑Benz: W169 and other models

Volkswagen: Crafter and other series

Since each manufacturer uses different sensors and calibrations, precise diagnosis and repair require deep, model‑specific expertise.

How is B1625 professionally repaired?

Professional repair of error code B1625 involves precise diagnostics using specialized software, restoration or replacement of defective components, and clearing fault memory entries along with any crash data. The control unit is then calibrated, subjected to final testing, and returned with 2 years' statutory liability for defects.

After submitting the removed control unit to Airbag24, the repair process begins with a thorough analysis. Using diagnostic systems, the fault is accurately localized to determine whether the root cause lies in the sensor, the wiring, or the control electronics.

In the next step, identified causes are addressed. This may involve repairing traces on the circuit board, replacing faulty parts, or restoring proper electrical connections. Stored crash data that could block the control unit is also carefully erased.

Following the actual repair, the control unit undergoes reprogramming and calibration. Final functional tests ensure that fault code B1625 has been completely resolved and the airbag system is functioning flawlessly once again. Two years' statutory liability for defects is provided on the repair.

Is Repair Worth It for Fault Code B1625?

Yes, repairing a vehicle with fault code B1625 is almost always the best option. It is significantly more cost-effective than purchasing a new airbag control unit directly from the manufacturer. Professional restoration restores the system’s full safety and functionality, making it a sustainable and economically sound solution.

Replacing an airbag control unit with a brand-new one often entails very high costs. Repairing the component can save up to 70% compared to the price of a new unit, without compromising safety or performance.

However, before proceeding with repair or replacement, it is crucial to have a qualified workshop verify whether the fault truly originates in the control unit. A thorough preliminary diagnosis helps avoid unnecessary expenses and ensures that the correct component is repaired.