U0456: Ungültige Daten vom Steuergerät der Kühlmitteltemperatur empfangen
Was zu tun ist
Watch the temperature gauge, and do not rely on it.
Modern engines control their own temperature actively rather than with a simple thermostat, because they want to run hot when cruising and cooler when working hard. This code means the module doing that is reporting something the engine computer cannot accept.
Usually the result is an engine that never properly warms up. You will notice a heater that takes far too long to give heat, higher fuel consumption, and possibly the engine light. That is not urgent but it is not harmless either — an engine running cold wears faster and uses noticeably more fuel.
The less common case is the one to be alert to. If the temperature reading has stopped responding, the gauge cannot warn you about overheating either, because it is fed from the same information. So trust the other signs: steam or a sweet smell from the engine bay, a heater suddenly blowing cold, or a coolant warning. Any of those means stop and switch off, rather than pressing on to the next town.
Check the coolant level when the engine is cold, and mention any other stored codes — one naming a coolant sensor or the water pump is very likely the real fault.
Was dieser Code bedeutet
The coolant temperature control module is broadcasting data that cannot be accepted as true. See U0400 for the family's framing.
Why a vehicle now has a module for coolant temperature at all is the thing worth explaining, because it is a genuine change from how engines used to work.
A wax thermostat has one opinion: open at one temperature. A modern engine wants several. It runs deliberately hot at light load, because a hotter cylinder wall burns more completely and loses less heat, and deliberately cooler under load, because a hot combustion chamber brings detonation forward. It also wants to warm the gearbox oil quickly from the same circuit, heat the cabin on demand, and on a hybrid or electric vehicle manage the battery's temperature within a narrow band. No wax pellet does that, so the job is done with an electrically heated or motor-driven valve, an electric pump, and a module coordinating them.
The consequence of an implausible report is asymmetric, and that is the practical content here. The engine module's safe response to a coolant figure it cannot trust is to assume the engine is hotter than it is: full cooling, valve open, fan on. That gives an engine which never reaches operating temperature — the P0128 picture, with its fuel consumption, its cold-running wear and its poor heater — and no warning light that says so, because nothing is overheating.
The opposite case is rarer and more serious. A temperature genuinely rising while the reported figure is stale means the gauge cannot warn you, because the gauge is derived from the same data. Steam, a coolant smell or a heater blowing cold are then the only signs, and they should be treated as instructions to stop.
As everywhere in this family, the module is usually reporting faithfully. A coolant temperature sensor, a valve position sensor or the electric pump's own feedback is the likelier fault, and any code naming one of those directly is the diagnosis.
Wahrscheinliche Ursachen
Hier anfangen
- Eingang des empfangenden Steuergeräts defekt · Fachwerkstatt
- Korrodierter oder loser Stecker · einfach
- Kabelbaum beschädigt · mittel
- Hitzeschaden an Sensor oder Leitung · mittel
Seltener
- Datenbusleitungen beschädigt · mittel
- Software nur an einem Steuergerät aktualisiert · Fachwerkstatt
Symptome
Beteiligte Bauteile
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