Fault code B1402 – a step-by-step guide to diagnosing and fixing it

Error code B1402 is displayed and the check engine light is on - what does this mean?

The DTC B1402 is a body control module fault code that is recognized by the OBD/EOBD system and indicates a problem with the airbag warning light system. This trouble code mainly affects the airbag warning light in the dashboard and its control circuit. Depending on the vehicle manufacturer, slight variations in the code definition may occur.

What causes can this fault code have?

• Defective airbag warning light in the dashboard
• Damaged wiring to the warning light system
• Loose or corroded plug connections
• Faulty body control module (BCM)
• Blown fuse in the airbag circuit
• Defective lamp driver in the control unit
• Short circuit in the wiring
• Overvoltage damage to the warning light system

What symptoms occur in parallel with fault code B1402?

• Airbag warning light does not work: The warning light does not light up or stays on permanently
• Missing system test: No lamp test is performed when the vehicle is started
• Intermittent illumination: The warning light flickers irregularly
• Other warning lights affected: Other warning lights may not be working properly
• OBD fault code saved: Fault code B1402 is stored in the fault memory

How to fix the problem of fault code B1402?

• Repairing EOBD fault code B1402 requires a systematic approach to diagnosing and rectifying the warning light problem.
• Checking and replacing the faulty airbag warning light in the dashboard, including removing the instrument panel and installing a new light
• Checking and repairing the wiring between the body control module and the warning light, with continuity testing of all cables and replacement of damaged cable sections
• Cleaning and securing all plug connections in the warning light circuit, with contact spray treatment and firm reconnection
• Replacement of the body control module in the event of an internal defect in the lamp driver, after prior coding and programming of the new control unit
• Checking and replacing the corresponding fuse in the fuse box, followed by a functional check of the entire system
• Repair of short circuits or earth faults in the wiring by selectively replacing affected cable sections