U0139: Kommunikationsverlust mit dem Fahrwerkssteuergerät B
Was zu tun ist
Look at the car from a few metres away before you drive it. If it is sitting low, or low at one corner, do not drive it — have it recovered.
This is the second of your car's suspension computers, and it has stopped talking to the rest of the car. On an air suspension that usually means the system can no longer keep itself pumped up.
Air suspension does not fail suddenly; it sinks. The bags always leak slightly and the compressor always tops them up, so when the topping up stops, the car settles over a few hours or overnight.
A car sitting on its bump stops has no suspension left at all. The ride is violent, the tyres can catch the arches, the headlights point at the road, and it does not handle the way anything about it was designed to. That is worth a recovery truck rather than a careful drive home.
Two things that save money. If the compressor is running constantly and the car still will not stay up, stop driving it — a compressor fighting a leaking air bag overheats and burns out, which turns one repair into two. And ask about a transport or jacking mode: most of these cars have one that holds a fixed height for recovery, which is far better than dragging a settled car onto a trailer.
Ask for the compressor's relay, fuse and earth to be checked first. They are the commonest cause and the cheapest.
Was dieser Code bedeutet
A second suspension control module has stopped being heard from. The general reasoning is at U0100; module A is at U0132, and U0421 covers the same family reporting implausibly instead.
A vehicle carries a second suspension module when the job has been split — commonly one per axle on a full air suspension, or a separate controller for the compressor and reservoir alongside the module that decides ride height. So this code usually means one end of the vehicle, or the air supply itself, has gone quiet.
Which produces the failure this page exists for: a vehicle that settles. An air suspension that cannot run its compressor does not fail suddenly — it sinks, over hours or overnight, as the bags leak the small amount they always leak and nothing replaces it.
A vehicle sitting on its bump stops has no suspension travel at all, and that is a genuine limit rather than a comfort complaint: the ride is violent, the tyres foul the arches on compression, the headlights point at the ground, and the handling is not what any part of the vehicle was designed around. If the vehicle is visibly low, or low at one corner, it should be recovered rather than driven.
One end low and the other normal is the signature of a split system and points straight at which module or which circuit is involved — worth photographing before it is moved.
Two practical notes that save money.
- Do not keep driving a system that is trying and failing to hold height. A compressor working against a leaking bag runs continuously, overheats and burns out — turning a bag repair into a bag and a compressor.
- Many vehicles have a transport or jacking mode that holds a fixed height for towing and recovery. Ask for it; it is much better than dragging a settled vehicle onto a trailer.
Where the fault is: the compressor and its relay live under the vehicle or in a wheel arch, and their supply is the single commonest failure in the whole system — a relay, a fuse, or a corroded earth, all cheap.
Wahrscheinliche Ursachen
Hier anfangen
- Sicherung durchgebrannt oder Versorgung ausgefallen · einfach
- Korrodierter oder loser Stecker · einfach
- Wasser in den Steuergerätestecker eingedrungen · mittel
- Kabelbaum beschädigt · mittel
Seltener
- Masseverbindung korrodiert · mittel
- Datenbusleitungen beschädigt · mittel
Symptome
Beteiligte Bauteile
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