ECU 028 906 021 AT: Where does it fit?

Translated on 29-10-2026, 4:40.

Engine control unit 028 906 021 AT - where does it belong?

According to the seller, it's a Passat with a 1Z engine, manufactured in 1996, with a mileage of 15,000 km.

Is that correct?

Thank you and best regards.
Jens.

Translated on 29-10-2026, 4:41.

mullemaus wrote:

Regarding the control unit, it should be one that was used from 1994 onwards. I mean, it might even be one without WFS.

I always thought that MSG (Message Service) without WFS (Web Feature Server) was only available starting with MSA15.
How can you find out if something is without a WFS?
(Okay, you can plug it in and try it out...)

Regards,
Jens.

Translated on 29-10-2026, 4:42.

Quote:

Is that correct?

Okay, please provide the text you would like me to translate from German to English.

Guest Free account, no CAN development support

I always thought that MSG without WFS is not available for MSA15 or higher.
It aligns with my experiences. The '94 Passat came standard with WFS on some models.
I'm pretty sure that one belongs to the 1Z group.

Best regards,
Rudi

Translated on 29-10-2026, 4:45.

Hi,
Did my 1Z engine have air in the diesel line?
Okay, I fixed it. Also, regarding the keywords, we have "leaks," "hoses," "filter," and the pump was from Bosch.

Föder started, began to sputter, vented through the nozzles, and then started running smoothly

.

The error memory shows error code 37 10, indicating a sporadic control unit defect.
It reappears immediately after being deleted.

Press the accelerator (makes a whistling sound like air being released) engine off

A friend of mine who works at VW mentioned the engine control unit.

The error could also be caused by the chip that is installed from the factory (Öttinger).
028 906 021 AT
0281001 368/369

Which engine control units (ECUs) are compatible?

Translated on 29-10-2026, 4:47.

B4 killler wrote:

...
A friend of mine who works at VW mentioned the engine control unit.

The error could also be caused by the chip that is installed from the factory (öttinger)

.
Can, but doesn't have to.

Quote:

028 906 021 AT
0281001 368/369
Which engine control units (ECUs) are compatible?

The 021AT was never officially replaced (and is therefore still valid).
However, other vehicle identification numbers included 021FC, 021FF, and 021FG.
I still have a TCU (Transmission Control Unit) that is compatible with the 021FC (if you are interested, please send me a private message).

Best regards, Micha.