U0645: Perda de comunicação com o módulo do defletor aerodinâmico ativo
O que fazer
Kneel down and look under the front bumper before you drive over anything.
Your car has a panel that lowers at speed to improve aerodynamics and retracts at low speed so it clears kerbs and ramps. The car has lost contact with it, which means it may be stuck in the lowered position — and a lowered panel meets the first steep driveway or car park ramp you use.
If it is hanging down, take ramps, kerbs and speed humps slowly and at an angle until it is repaired. Replacing the panel costs far more than reconnecting it.
Nothing else about the car is affected — it drives normally, and fuel consumption may rise very slightly on a motorway. This is one to book in rather than worry about.
Mention it if the car has been through deep water, driven on salted roads, or grounded on anything. The module sits in the most exposed spot on the vehicle and corroded connectors are the usual cause.
O que este código significa
The active air dam module has stopped communicating.
This range exists because parts stopped being parts.
A lost-communication code at U01xx or U02xx means a control module went silent — a computer, with a processor and a name. This range says the same thing about a coolant pump, a valve, or a sensor, and that sentence only became possible when those components acquired controllers of their own.
Most of them are not on the main CAN bus. They hang off a LIN sub-bus — a single-wire, low-speed network that a master module runs to a chain of small devices, precisely because giving every actuator a full CAN interface would be absurd. LIN is cheap, slow, and has one property that dominates diagnosis: it is a chain.
Which produces the most useful fact about this whole family. The fault is very often not in the part named, and not even in its wiring. A LIN chain shares one wire, one supply and one master:
- One device silent, the rest talking — the fault is that device or its connector.
- Several devices on one chain silent together — the fault is the shared wire, the shared supply, or the master module that runs them. Replacing any one of the named parts fixes nothing.
So read every other stored code before touching anything. On this family more than most, the pattern across codes is the diagnosis, and a single code in isolation means something quite different from three that arrived together.
These devices are also, physically, the ones in the worst places — bolted to engines, in wheel arches, under the front bumper. Heat, vibration, salt and water reach them in a way they never reach a module behind a dashboard, so connector corrosion is a leading cause here rather than an afterthought.
An active air dam is the panel that lowers itself below the front bumper at speed, and most drivers have no idea their car has one.
It exists for aerodynamics. Air passing under a car is turbulent and generates lift and drag; a deployable dam blocks it at motorway speeds, cutting drag by enough to matter for fuel figures and emissions certification. It retracts at low speed so that the car can clear kerbs, ramps and speed humps without tearing it off.
Which produces the one genuinely practical consequence of losing communication with it: a dam that may be stuck down. A panel deployed at parking speeds is exactly what a kerb, a steep driveway or a car park ramp will remove, and the failure is silent because nothing about the car feels different.
So the useful instruction is to look. Kneel at the front of the car and see whether a panel is hanging below the bumper. If it is, treat every ramp and kerb with care until it is fixed, because the repair is far cheaper than the panel plus whatever it catches on.
Road damage is also the leading cause rather than a rare one. This module and its motor live in the lowest, most exposed position on the vehicle, collecting salt spray, standing water and gravel — a place where connector corrosion is close to inevitable.
Causas prováveis
Comece aqui
- Conector corroído ou frouxo · fácil
- Fiação do barramento de dados danificada · moderado
- Chicote elétrico danificado · moderado
- Dano físico por detritos da via · moderado
- Infiltração de água no conector · moderado
Menos comum
- Alimentação ou massa do módulo inoperante · moderado
- Dano térmico ao sensor ou à fiação · moderado
- Conexão de massa corroída · moderado
Sintomas
Componentes envolvidos
Informação, não instrução
O CarGeek é uma referência, não um manual de serviço. Suas páginas são escritas a partir de fontes públicas e do que outras pessoas constataram, nunca a partir da documentação de serviço do fabricante, de modo que podem estar erradas ou incompletas para o seu veículo específico. Parte do que descrevem envolve risco real: alta tensão, combustível sob pressão, energia acumulada e peças quentes ou em movimento.
Antes de agir com base em qualquer orientação, peça a verificação de uma pessoa com formação técnica, seguindo o procedimento do próprio fabricante para o seu veículo. Nada aqui substitui esse procedimento.
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