P2544: Eingangssignal A der Momentenanforderung
Was zu tun ist
The usual complaint is an engine that will not pull — flat, slow to respond, sometimes limited to a low speed — and sometimes harsher gearchanges instead. The important thing to say to whoever looks at it is that this code is not about the engine. It is about a wire on which another module asks the engine to back off, and a fault there produces a perfectly healthy engine that behaves as though it is broken. Do not agree to spark plugs, coils, injectors, a fuel pump or a turbocharger on the strength of this code — none of them would change anything. Mention any warning light for traction or stability control, and mention whether the gearchanges have altered, because both narrow down which module is at the other end of the wire.
Was dieser Code bedeutet
A fault in the circuit by which another module asks the engine module to reduce engine torque.
The engine module is not the only thing that decides how much power the engine makes, and this is the wire by which it is overruled. Several systems need the ability to take torque away, quickly and without asking the driver:
- The transmission module, during every gearchange. Cutting torque for a few tens of milliseconds while one clutch releases and another takes up is what makes a modern automatic shift smoothly instead of banging. The driver never knows it happened.
- The stability and traction control module, when a wheel spins or the car starts to slide. Closing the throttle is faster and finer than any driver could manage by lifting off, and it is the intervention those systems reach for first.
- The braking system, on vehicles where brake authority over the engine is arbitrated outside the engine module.
Signal A is normally a dedicated wire rather than a message on the data bus — an analogue voltage or a duty cycle — precisely so that a safety-relevant torque cut does not depend on the health of a network shared with the radio.
Here is why this code matters more than its title suggests: when this circuit fails, the engine loses power for a reason that is not in the engine. A request line that has drifted, chafed or shorted reads as reduce torque now, continuously, and the engine module obeys — because ignoring a torque reduction request is not a safe default. The driver gets a car that will not pull. The compression is fine, the plugs are fine, the injectors, the filters and the turbocharger are all fine, and every one of them can be replaced without changing anything.
The failure in the other direction feels like nothing at all, and is still worth fixing. An open request line means the reduction never arrives — so gearchanges become harsh, because the torque cut that smoothed them is missing, and traction control loses its most effective tool at the moment it needs it. A car with this code and harsher shifting is not a coincidence of two faults.
This is the P0700 argument arriving by a different road: the module reporting the fault is not the module that has it.
Wahrscheinliche Ursachen
Hier anfangen
- Kabelbaum beschädigt · mittel
- Korrodierter oder loser Stecker · einfach
- Leitung mit Masse kurzgeschlossen · mittel
Seltener
- ESP-Steuergerät defekt · Fachwerkstatt
- Getriebesteuergerät defekt · Fachwerkstatt
Selten
- Motorsteuergerät defekt · Fachwerkstatt
Symptome
Beteiligte Bauteile
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