Audi A3: Common Electronic Problems

Hello forum!

Since my, now aging, A3 has decided to start falling apart, several problems have arisen that I can't find solutions for in individual articles.
I hope you can give me some tips on what might be going on.

Vehicle: Audi A3, Year: 04/2000, Engine: 1.9 TDI, Power: 110 hp.

Problems:
"The airbag light is constantly on, even though I haven't read out the control unit (apparently, there are issues with the airbag control unit in my model series). Once, I had to reconnect a broken wire under the seat, but that's not the problem now."
2. The ABS light is constantly illuminated (there were no problems with it until recently). The ABS system is not working.
3. The brake wear indicator light is constantly on (I disconnected the connector. Even though there is no wear, the light is still on).
4. The engine rattles excessively when starting and when reversing (possibly due to engine mounts or rubber buffers?).

Reading the engine control unit with my laptop revealed no error codes in the memory.
I don't use VAG-COM, but rather WBH-DIAG version 0.88, because of my old interface (opto-coupler).

I hope you can help me troubleshoot this, otherwise I won't be able to get any more pimples.

HI,

1. Read the error codes, and then you'll know which one is the culprit. 'Clip the broken wire under the seat back together' - that sounds reassuring .

2. Also, it's likely a faulty speed sensor. It's relatively easy to replace, but you'll probably need to use a diagnostic tool to read the error codes. Without reading the codes, it's just guesswork.

Okay, so regarding point 3: If the pads are okay, then check the connectors. You can try disconnecting and bridging them to see if it works with or without the bridge. Otherwise, follow the cables, as they sometimes have breaks, even in the wheel well or at the cable passages. I've experienced that myself before.

4. 'Rattert' - what exactly? Are we talking about knocking or rattling? - You can check the engine mounts with 2 people. Have one person engage the handbrake while the other looks in the engine compartment to see if the engine moves excessively when trying to start with the handbrake engaged. Also, check it while reversing. I would say that about 2-5 cm of 'play' in the engine is acceptable. You might also hear a noise if it's hitting something.
Otherwise, the driveshaft or joint could also be the cause of the rattling. Check if it gets worse when turning.

Greetings.

Hello,

4.
The entire car vibrates. The problem only occurs when engaging the clutch, whether starting forward or reversing. However, it's worse when the steering wheel is turned.


Bertl100

Also, I'm checking the error codes. My first thought was that it might be a problem with the dual-mass flywheel or that the clutch springs are broken.

Greetings.