B1440 airbag control unit fault

What does error code B1440 mean?

The B1440 error code in the airbag control unit (SRS) indicates a critical electrical fault: a short circuit in the wiper mode selector switch circuit to the battery. Although the root cause lies outside the airbag system, this fault can impair the entire safety system’s functionality and even lead to its deactivation, posing a significant safety risk.

Technically, the airbag control unit detects an abnormal voltage in the circuit connected to the windshield wiper selector switch. This error code is not exclusive to the SRS control unit and may also be logged in other modules, such as the instrument cluster or the comfort control module, if a short circuit is detected there as well.

In the context of the airbag system, storing error B1440 is particularly critical. The control unit interprets the short circuit as a potential malfunction that could jeopardize the reliable deployment of airbags in the event of a crash. For safety reasons, the system is often placed into a passive state.

How do you recognize error B1440?

The most obvious symptom of error code B1440 is a continuously or intermittently illuminated airbag warning light (SRS symbol) in the cockpit. In many cases, the airbag control unit can no longer communicate with diagnostic tools, suggesting that the airbag function may be completely disabled.

The glowing SRS warning light is the vehicle’s direct prompt to have the safety system inspected immediately. It will not extinguish after restarting the engine as long as the fault remains active.

Another indication may be the storage of additional error codes in the fault memory, pointing to a general system failure or communication issues between control units. The functionality of the windshield wipers themselves may be affected—but does not necessarily have to be.

What causes error code B1440?

The primary cause of error B1440 is a physical short circuit in the wiper mode selector switch circuit. This is usually triggered by defective cables, corrosion‑induced connector damage due to moisture, or mechanical damage to the switch itself. Overvoltage in the vehicle’s electrical system—such as from jump-starting with reversed polarity—can also trigger this error.

Very often, damaged cable insulation or broken wires occur in the steering column area where the wiper switch wiring runs. Constant movement over time can lead to wear and tear in this region.

Water or moisture ingress is another common cause. When water enters the switch connectors or even the control unit itself, leakage currents and short circuits may develop, triggering error code B1440.

Rarer but equally possible is overvoltage caused by using faulty chargers or improperly connected batteries. Such voltage spikes can damage sensitive electronic components.

Which models experience error B1440?

Error code B1440 has been reported in a range of vehicles from various manufacturers. Affected models include those from Peugeot, Dacia, Mazda, Lexus, Rover, and Toyota. Airbag24 has expertise in repairing this fault for specific model series such as the Peugeot 607, the Mazda MX-30, or the Lexus ES and LX.

At Airbag24, we repair control units exhibiting error B1440 for the following vehicles:

Dacia: 1325 I

Lexus: ES ES300, LX LX570

Mazda: MX-30 e-SkyActiv

Peugeot: 607 I (model years 2000–2004 and facelift 2004–2010)

Rover: Range Rover Classic

Toyota: Vitz XP90, Sequoia TRD Pro, Previa XR50

Typical part numbers potentially affected by this fault include, depending on the model: 5WK44740, 5WK44004, 5WK44320, A2049012604, A2048706826, or A2049012704.

How is error B1440 professionally repaired?

A professional repair of error B1440 focuses on eliminating the underlying electronic cause. After sending the control unit to Airbag24, it is opened and analyzed at the circuit board level. Defective cables, connectors, capacitors, or damaged traces are expertly replaced. Finally, the fault memory is cleared, and the device is thoroughly tested for full functionality, backed by a 12-month warranty.

The process begins with reading the fault memory using manufacturer‑specific diagnostic equipment (e.g., Bosch, Gutmann, or Snap-on) to clearly identify error B1440 and analyze any accompanying codes.

After removal and shipment of the control unit, Airbag24 performs a thorough visual inspection of the circuit board and all components. Using specialized tools, we detect short circuits, defective capacitors or resistors, and damaged traces.

The actual repair involves replacing the faulty components. If a short circuit is caused by the wiper switch, the affected cables or connectors are repaired or replaced. In cases of severe overvoltage damage, a more extensive repair may be necessary.

Following successful repair, the control unit’s fault memory is completely cleared. The refurbished module is reinstalled in the vehicle and subjected to a functional test to ensure that the airbag warning light goes out and the system is fully operational again.

Important Safety Notes for Repair

Work on the airbag system is safety-critical and must be performed exclusively by trained professionals. Improper interventions can lead to unintended airbag deployment or failure in an emergency. The use of simulators or bypass resistors is life‑threatening and illegal.

Never attempt to open or repair the airbag control unit yourself. The capacitors installed inside the unit can still carry high voltage even with the battery disconnected.

The use of inexpensive diagnostic tools purchased online is not recommended, as they often cannot accurately read and interpret all manufacturer‑specific fault codes. This can result in misdiagnosis and unnecessary expenses.

Avoid any manipulation of the system, such as installing airbag simulators or resistors to deactivate the warning light. Such modifications only simulate a functioning system while effectively disabling it and leading to the loss of the vehicle’s operating permit.