Fault code B1520 – a step-by-step guide to diagnosing and fixing it

The meaning of error code B1520 – Hood Switch Circuit Open

B1520: Causes, signs and repairs

Error code B1520 is displayed and the check engine light is on - what does this mean?

DTC B1520 is a body code that is recognized by the OBD/EOBD system and indicates a problem with the driver airbag circuit. This fault code affects the airbag control unit and the associated components of the occupant protection system.

What can cause this fault code?

Defective airbag control unit
Damaged driver airbag
Broken cable connections in the airbag system
Corroded plug connections
Defective slip ring in the steering wheel
Faulty ground connections
Damaged airbag coil cable
Defective crash sensors

What symptoms occur in parallel with fault code B1520?

Airbag warning light: Continuous illumination of the airbag indicator light in the dashboard
Function failure: The driver's airbag may not be functional
Warning tone: Audible warning signals when starting the vehicle
System error: Other safety systems may also be affected
Steering wheel problems: Irregular function of the steering wheel buttons

How to fix the problem of trouble code B1520?

Repairing trouble code B1520 requires a systematic approach to the airbag system.
Checking and replacing the airbag control unit after full diagnosis of the control unit software
Replacement of the driver's airbag including removal of the steering wheel and professional installation
Repair or replacement of damaged cable connections in the entire airbag system using special tools
Cleaning and treatment of corroded plug connections with contact spray and sealing
Replacing the slip ring in the steering wheel after removing the steering column
Checking and repairing the ground connections of the airbag system to the body and engine
Replacement of the airbag coil cable with factory spare parts and correct centering

FAQ - Frequently asked questions about DTC B1520

Can I continue driving with fault code B1520?

Continuing to drive with code B1520 is not recommended, as the driver's airbag may not be functional. In the event of an accident, there is an increased risk of injury to the driver.

How much does it cost to repair fault code B1520?

The repair costs for error code B1520 vary between 200-800 euros, depending on the defective component. A new airbag control unit costs around 300-500 euros, while a driver's airbag can cost 400-600 euros.

Can fault code B1520 be caused by a weak battery?

Yes, a weak or faulty battery can trigger EOBD code B1520, as the airbag system requires a stable power supply. Check the battery voltage first.

How long does it take to repair fault code B1520?

Repairing the DTC B1520 takes between 1-4 hours, depending on the cause. A simple connector repair is quicker than replacing the airbag control unit.

Can I repair fault code B1520 myself?

Work on the airbag system should only be carried out by qualified specialists. The system works with pyrotechnical components that can be dangerous if handled incorrectly.

Will the code B1520 reappear after the repair?

After a professional repair, error code B1520 should not occur again. If it does, there may be an additional defect that requires further diagnosis.

Vehicles in which fault code B1520 occurs most frequently

Fault code B1520 is a body code of the airbag system and can occur in various vehicle manufacturers, but is most common in the following vehicles:

Ford: Focus, Fiesta, Mondeo, Kuga (2005-2015)
Mazda: 3, 6, CX-5, CX-3 (2008-2018)
Volvo: S60, V70, XC90, S80 (2003-2012)
Jaguar: XF, XJ, F-Type (2009-2016)
Land Rover: Discovery, Range Rover, Freelander (2006-2014)
Lincoln: MKZ, Navigator, Continental (2007-2017)

If code B1520 occurs in your vehicle, you should visit a specialist workshop immediately. The airbag system is a safety-critical system that should only be repaired by trained technicians. A diagnosis with a professional OBD scanner is the first step to rectifying the problem. Do not delay the repair, as your safety on the road depends on it.

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