Defective Airbag Control Unit: Causes & Fixes

Hello fellow mechanics!

Skoda Octavia 1U2, 66kW, 1.9 TDi, Sedan.
My airbag light came on last week... I thought it was the usual sporadic contact error of the connectors on the underside of the seats. I disconnected and cleaned them, and then I wanted to go to the to have the error code cleared.
However, this time the error message '65535' indicated a defective control unit. The dealer suggested that it should be replaced.

Okay, here's the translation:

'Now, my question for those with experience in electronics: is it possible to use a used control unit with the number...'
'I want to buy part number 1J0909603 (which is also used in other Volkswagen group companies), but will it fit directly, or do I need to consider the model and equipment variant, and also reprogram the coding (65)?'

Thank you in advance. Best regards, Kylie

I would definitely not recommend buying a used engine control unit (ECU). I believe it costs around 300-400 euros new. Is your life not worth that? You should only buy a used one if you know its exact origin, otherwise, don't!

I had the same problem, and following a friend's (VW) advice, I bought one from an online marketplace. Everything matched the specifications (which is what VW would have ordered - the successor model had a different part number, as the problems are well-known). The replacement took only 5 minutes, and I haven't had any problems since.

Tribu wrote:

never had any problems again.

Of course not. The problem usually arises when you need it most, namely in an accident when the airbags might not deploy.

I don't want to speak badly about everything. Of course, it's possible to buy a used control unit that's in excellent condition. However, it's also possible to buy junk that looks like it works but doesn't. It's a risk that I personally wouldn't take.

You're right, it's really a matter of opinion. Personally, I think if there are no error messages and the light comes on when you start the car, then turns off, it's probably okay.
I can live with that hehe, that fits perfectly.

If you're not sure, you can always buy a new one.

Since my entire car is not even worth 3000 euros, and I'm constantly facing new problems every month, I'm not really keen on investing 300-400 euros. And then there are the additional costs for the installation.
But now, to get back to my question:
'Now, my question for those with experience with electric vehicles: is it possible to use a used control unit with the number...'
'I want to buy part number 1J0909603 (which is also used in other Volkswagen group companies) and I'm wondering if it will fit directly, or if I need to consider the model and equipment variant, and also reprogram the coding (65)?'

Best, Kylie

Most of the time, VW installs a "new" control unit, meaning it's not the same part number as the original.
Go to a Volkswagen dealership, get the part number for the replacement part, and then obtain that control unit.
You can find them for cheap on eBay. And I didn't have to do any reprogramming or anything like that.
The part number matched, and it worked correctly as a result.

Okay, I completely understand the motivation for buying a used part. Especially when a new part represents a significant cost of the overall vehicle. However, I imagine that VW might use the same control units for certain airbags, even across different vehicle models. Of course, the coding would definitely be different, because I can't imagine the triggering conditions being the same in a Passat as, for example, in a Polo. Different values might be programmed. The parts listed on online marketplaces have likely already been triggered in an airbag deployment, because who would disassemble a car that's still running and offer those parts for sale?

matthiasTDI96 wrote:

The devices from the online marketplace likely all had their airbags deployed at some point, because who would disassemble a car that's still running and offer those parts for sale?

A) The person who claims the scrapping bonus but only has the body of the car scrapped, while first removing everything that is still sellable.
B) The person whose car is no longer working.
C) Recycler of damaged vehicles.

It's not unreasonable to consider scrapping a car worth €3-4,000, even without removing the airbags (e.g., due to rear-end damage, engine failure, or to claim a scrapping bonus).

Despite my own arguments, I agree with you that many items on eBay have likely triggered [something].

Best regards,
Guste.

...and that's exactly what I mean...

Why not check at a junkyard? There are always cars there with rear-end damage, etc., whose airbags are still functional... and in my opinion, their control units should actually be okay.

I agree, but I understand what he means. It's just a matter of perspective.
That's just how life is .

I have now replaced my airbag control unit with a cheaper one from WeeBaY*.
The airbag light is now off, so it seems everything is okay.

I will go to the mechanic later today to have it reprogrammed and the error code cleared.

Is it really necessary to re-code the device, even though the indicator light is no longer on?

Best, Kylie

hi...

Okay, you don't need to clear any error codes because the light is off, and there aren't any errors stored (since it's a different control unit).

You don't need to recode anything, because if it didn't work, you would have gotten an error.
I guess you didn't buy any replacement parts, so you successfully repaired it.

Congratulations .