Passat B7 allroad wheels locked up

Hello
My friend owns a B7 allroad Passat with DSG 4 motion.
Few days ago he was driving slow and all 4whells locked up (totaly stoped turning).
It seems to be a mechanical fault, as there is no DTC.
Does anybody have an idea what could it be? The car is sitting as the wheels cant turn.
Thanks in advance.

Mechanically or electrical, is tough to determine.

I’m guessing the Passat use a Haldex system similar to the Golf Alltrack which we get in the states with the Gen 5.

My understanding of the Gen5 Haldex system is the rear diff and controller is entirely independent of the front except for the ability to couple the prop shaft to the rear axles via a hydraulic pump (pressure needs to be applied to make the connection). In the failures I’ve seen reported for the Haldex rear diff, is isn’t until excessive front tire spin is reported does the owner know there is a problem.

So for all 4 wheels to “lock up” I’m guessing an ABS fault, possibly in combination of the hill hold feature, or the hill decent feature the Alltrack probably has.

Long story short, read codes and see if there’s anything stored.

It was the “reducer” (reductor). The bearing inside was stuck.