Seatbelt Pretensioner Working Principle and Replacement Cost


If you get into an accident in any modern car, its seatbelt system will keep you secure in your seat so that you don’t get jerked forward or fly out of the windshield. Of course, this can only happen if you are complying with the law by wearing your seatbelt. If so, the seatbelt system has a component called the “seatbelt pretensioner” which keeps the seatbelt locked down during an accident. That is why a seatbelt does not stretch or have any slack when it is pushed forward quickly.

Working Principle

When your vehicle gets into an accident, there is a sudden deceleration that takes place. There are sensors in your vehicle which detect this sudden deceleration. Once they do, the seatbelt pretensioner sends a force which moves a concealed piston in your seatbelt system. The piston will then quickly turn a spool, causing the seatbelt strap to get wrapped around it. This entire process happens within less than a second. The seatbelt strap will basically lose all its slack, making it impossible to move. Since you are underneath this belt, you stay safely secured in your seat while the impact of the accident occurs.

As you the driver and front passenger stay secured in their seats, the airbag system will deploy its airbags in front of them. The seatbelt and airbag systems work together to keep everyone in the front safe. If you were not wearing your seatbelt in an accident, the airbag would not be able to save you. The force of the impact would be so strong that you would jerk forward or fly out the window before the airbag could even completely deploy. By staying strapped down to your seat, it ensures that your body is positioned directly in front of the airbag so that it can reduce your physical blow as much as possible.

Read also: Top 4 Symptoms of Failure Connecting Rod in Your Vehicle

Replacement Cost

You will need to replace your seatbelt pretensioner each time you get into an accident. The seatbelt pretensioner is not that expensive, so don’t worry about it. The replacement cost of a seatbelt pretensioner is only about $165. The cost of the parts is $65 while the cost of the labor is about $100. You may be able to reduce the labor if you can find a cheap enough mechanic in your area. But if you have just a little bit of mechanical skill, you could elect to do the replacement job yourself.


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