Airbag Repair and Diagnostics

The airbag is an integral safety system installed in the vast majority of all modern cars sold in Europe. Their function is simple – yet incredibly effective in preventing serious injury in the case of an accident. Impact sensors placed around the car measure the force of all collisions or events experienced by the vehicle. If these sensors detect a collision forceful enough to cause injury, they trigger the ignition of a solid propellant with a hot spark, generating inert gas, which fills the airbag.

This gas forces the airbags to inflate and emerge at approximately 200mph from their housing (airbag placement varies from vehicle to vehicle), and is released through small holes which allow the bag to act as an impact absorber, rather than a solid object from which the passenger could deflect.

The speed at which the airbag inflates allows this process to occur in mere milliseconds, meaning the bag is ready for passenger impact before it takes place.

The illumination of the airbag light or presence of an airbag warning notification on the console can indicate a number of issues with the airbag system, including, but not limited to;

Seatbelt Sensor Interference – the presence of foreign objects or debris in the seatbelt catch can indicate to the vehicle’s sensor system that the seatbelt is not fastened whilst in use, which often leads to the illumination of the airbag warning light.

Damaged under-seat wiring –internal wiring can often be damaged by actions as simple as placing objects under the driver and passenger seat. Damage to under-seat wiring in particular can cause the system to detect a fault in the vehicle’s airbags.

Damaged clock spring – The clock spring is an important part allowing for the turning of the steering wheel whilst maintaining a connection to the electrical system, horn, and most importantly, in this case, the airbag. A damaged clock spring can lead to disconnection from the airbag system, illuminating the airbag warning light accordingly. This is particularly common in older cars and often requires assistance from a specialist to rectify.

Previous accident – If the vehicle has already been in an accident in which the airbag was not triggered, the SRS warning light may stay illuminated until resetting is possible. Additionally, if the car has previously been flooded, wire corrosion may be to blame.

If your vehicle’s airbag light is illuminated, it is important to determine whether or not the cause is serious or minimal, and act accordingly. Auto Service & Tuning Centre is highly trained in airbag replacement and repair. Contact us, and one of our friendly advisors will be happy to assist in arranging a booking or provide further information regarding any of our services.

Airbag sensors are an integral part of the vehicle safety system. The most important parts of the success of the airbag system are the crash sensors. These small pieces of electronic equipment are placed around the car and measure the force of all collisions or events experienced by the vehicle. If these sensors detect a collision forceful enough to cause injury, they trigger the ignition of a solid propellant with a hot spark, generating inert gas, which fills the airbag.

There are two primary types of airbag sensors, those with a ‘ball and tube’ mechanism, and those with a ‘metal roller’ spring-loaded weight, or accelerometer. The ‘ball and tube’ mechanism consists of a small tube containing a circuit switch and ball, held together by a magnet. If a collision forceful enough to dislodge the ball from the magnet occurs, the airbag will be triggered. Other, newer electrical designs work in a similar way, using alternative methods.

Mechanical sensors are designed to include a firing pin, which triggers a small explosion following a forceful enough collision. These sensors do not require an electrical power source, so cannot be deactivated like electrical sensors.

Airbags must be able to deploy within milliseconds of the sensors detecting a forceful collision in order to work effectively. The average deployment time of an airbag is around 55 milliseconds, though this can vary slightly, with the discussion to deploy being made within 15-20 milliseconds of the first signs of a collision. In comparison to this, the average collision lasts from 120-170 milliseconds, meaning the airbag is fully deployed prior to major engagement.

Airbag replacement is somewhat of a grey area. When the system was first popularised in the 1990s, many manufacturers advised a shelf life of 10-15 years, whilst others suggested airbags would last for the lifetime of the vehicle. This variation was a result of the inability of most manufacturers to establish a set lifetime for this safety feature.

Airbags used in modern cars are generally considered to be robust, and relatively resistant to wear and tear. They are able to be reset after accidents in most cases, meaning replacements are generally redundant. Most airbag replacements occur as a result of over-inflation in an accident to the extent that the airbags cannot be reset.