U3000: Steuergerät
Was zu tun ist
Have the battery and its connections tested before anything else is touched — including the battery terminals themselves, cleaned and retightened.
That sounds too simple for a code like this, and it is still the right first step: a battery weak enough to sag while cranking, or a terminal corroded under a clamp that looks perfectly tight, produces this entire family of faults exactly. It is the cheapest thing to rule out and the most common cause by a distance.
If the car has a page of unrelated warning lights, expect most of them to clear when this is fixed. A module with a poor supply reports nonsense about everything it watches, so one bad connection can light up half the dashboard.
Mention two things: whether the car has had a flat battery or a jump start recently, and whether any bodywork or accessory fitting has been done. A body shop that bolts an earth strap onto fresh paint makes a connection that looks perfect and conducts badly — and that is a classic cause.
Was dieser Code bedeutet
A control module is reporting a fault with itself.
This range is different from every other network family, and the difference decides how it should be diagnosed.
U01xx and U02xx say a module went silent. U04xx and U05xx say a module is talking nonsense about something it watches. This range says a module is reporting a problem with its own foundations — its supply, its earth, or the ignition state that tells it whether the car is even meant to be awake.
Which makes these codes upstream of almost everything else. A module with a marginal earth does not fail cleanly; it reports implausible values about every sensor it reads, sets codes in unrelated systems, and drops off the bus intermittently. A scan tool showing thirty codes across five systems very often has one of these underneath it.
So read this family first and fix it first. Clearing a page of downstream codes before the supply fault is repaired produces a page of downstream codes again by the end of the week.
And start with the battery, genuinely. Not as a formality — a twelve-volt battery weak enough to sag during cranking, or a terminal with corrosion under a clamp that looks tight, reproduces this entire family exactly. It is the cheapest thing to eliminate and by some distance the most common cause.
This is the family's front door, and it is deliberately unspecific.
It says a module has failed an internal check without narrowing which check — power, memory, processor, or its own self-test at wake-up. Every other code in this range is a more precise version of it, which makes it far less useful than whatever else is stored alongside.
So the diagnostic instruction is short: read the other codes. This one on its own, on a car with a healthy battery and no other symptoms, is frequently a record of a moment rather than a live fault — a voltage dip during cranking, a jump start, or a battery disconnected while the car was awake.
Where it repeats after being cleared, and the supply has been proven good, it starts to mean what it says. Modules do fail internally; that conclusion is simply the last one rather than the first.
Wahrscheinliche Ursachen
Hier anfangen
- Zu niedrige Systemspannung · einfach
- Korrodierter oder loser Stecker · einfach
Seltener
- Steuergerät nicht auf das Fahrzeug codiert · Fachwerkstatt
- Programmierung des Steuergeräts abgebrochen · Fachwerkstatt
- Datenbusleitungen beschädigt · mittel
Symptome
Beteiligte Bauteile
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