I have bought a used Superb which was modified by the previous owner. The car has had it's knee airbag deactivated. The cable is no longer connected. Everytime I turn the car on I get the message: Seat belt air bag tensioner deactivated. I am not sure if the message is related to the airbag being disconnected but it might be. My question: can I simply plug it back in?!

Sorry i know nothing about your car, but is the no Key for turning off for having a Child Seat in the front seat.

Or does that have a different message? 

Seat belt pretensioners are not airbags although they both use pyrotechnic charges and are triggered by the same controller.

 

I did not know that airbags could be deactivated other than the passenger dashboard one for when a baby seat is used on the front passenger seat, this is done by using the ignition key in the switch within the glovebox (on my vehicle) are you sure the warning is not because that is switched off?

 

A VCDS scan would reveal all, do you have the airbag warning light illuminated? If so you will need VCDS or equivalent to find out why and turn the light off (its latching) after the remedial work has been done, I think you should start there because the previous owner has been mucking around with the safety system if he is to be believed.

 

Have you checked the V5 for a category letter to make sure the vehicle was not an insurance write off? Knee airbag deactivated sounds like someone not willing to pay to do the repairs properly and have used a shunt resistor instead of the airbag.

The car was modified by the dealer when it was brand new. The driver knee airbag was turned off because the owner was handicapped.

 

I checked under the steering wheel and I saw that it is disconnected. My question is if I can simply plug it back in.

14 hours ago, MikeKaroq said:

My question is if I can simply plug it back in.

It's really impossible to answer that without knowing how the dealer modified the car from new.

 

There's a risk that plugging it back in could cause it to inflate explosively...

Hey basically unplugged it. There are two wires that go into the plug. He added a device on one of the wires so it doesn't show a permanent error on the dash. That's as far as I know. 

14 hours ago, MikeKaroq said:

Every time I turn the car on I get the message: Seat belt air bag tensioner deactivated.

I'd want to get this message understood, and cleared if possible, before doing anything with the knee airbag.

 

If there's a "device" on the knee airbag wires then that suggests that either there's another fault or the device isn't working properly.

 

Get a fault code scan done, and understand what's going on before making any changes is my advice.

Edited 28 August, 20241 yr by PetrolDave

2 hours ago, PetrolDave said:

17 hours ago, MikeKaroq said:

Every time I turn the car on I get the message: Seat belt air bag tensioner deactivated.

I'd want to get this message understood, and cleared if possible, before doing anything with the knee airbag.

 

Agreed.

 

2 hours ago, PetrolDave said:

If there's a "device" on the knee airbag wires then that suggests that either there's another fault or the device isn't working properly.

 

Not if the warning has nothing to do with the shunt resistor bodge which I am sure is the case, as you said above the OP should resolve the problem regarding the seat belt pre-tensioner before making the knee airbag operational again.

 

I am suspicious that he is being fed a line and that the airbag was shunted because it was faulty or perhaps the real problem is the airbag control module showing up errors for the connected devices, we have one or two handicapped people on the forum one with a prosthetic leg, would there ever be a circumstance where a knee airbag should be deleted for a handicapped owner?

 

17 hours ago, MikeKaroq said:

My question is if I can simply plug it back in.

 

If it was not faulty, if the "device" is inserted in its place then removing the device with the battery disconnected and plugging the airbag back in should be OK if the airbag was not faulty there is no danger with doing it with the battery connected but that would bring up a MIL light requiring resetting with VCDS or equivalent.

 

You did not answer my question is the airbag warning light illuminated?