P2400: Bomba de detecção de vazamentos do sistema de emissões evaporativas — circuito de controle aberto
O que fazer
The car will drive normally; this is an emissions monitoring fault and will fail a test rather than affect running. A humming or ticking noise from the car some hours after it is parked is this system working, not a fault — worth knowing before anyone pays to investigate it. If the battery has been going flat overnight, mention it: a pump that keeps retrying because it cannot complete its test is a real cause of that. Ask for the connector and wiring under the vehicle to be inspected before the pump is replaced — they sit in the road spray and account for most of these.
O que este código significa
An open circuit in the control of the evaporative system's leak detection pump.
Why a pump exists purely to look for leaks. The evaporative system captures fuel vapour from the tank so it burns in the engine rather than escaping. Regulations require the vehicle to prove that system is sealed, and to find holes as small as about half a millimetre — a hole you could not see, and which no ordinary sensor would notice.
There are two ways to test for something that small. One is to use the engine's own vacuum: seal the system, draw it down, and watch whether the vacuum decays. The other is a dedicated pump that pressurises the system with air and reports how hard it has to work to reach and hold pressure. A pump that reaches pressure quickly and holds it has found a sealed system; one that pumps forever without getting there has found a hole, and how long it takes indicates the size.
The property worth knowing about the pump approach is that it works with the engine switched off — typically some hours after shutdown, once the fuel has stopped sloshing and temperatures have stabilised. Vapour pressure changes with temperature, so a test run on a hot, freshly driven tank measures the weather rather than the seal.
Three consequences follow, and two of them regularly get reported as faults:
- A parked car can hum or tick to itself hours after being left. In a quiet garage overnight this is audible and alarming, and it is the system doing exactly what it should.
- The test needs the car to stand. A vehicle used only for short journeys and rarely left long enough may never complete its evaporative monitor, which can mean being refused an emissions test for incomplete readiness rather than failing anything.
- A pump that never satisfies its test keeps trying, and that is a genuine cause of a battery going flat overnight on a car that is otherwise healthy.
The fault itself is usually mundane. The pump lives underneath the vehicle near the charcoal canister, in the road spray and salt, so its connector and wiring account for a large share of these.
Causas prováveis
Comece aqui
- Conector corroído ou frouxo · fácil
- Circuito aberto na fiação da bomba · moderado
- Bomba de detecção de vazamento do EVAP com defeito · moderado
Menos comum
- Chicote elétrico danificado · moderado
- Fusível queimado ou alimentação inoperante · fácil
Sintomas
Componentes envolvidos
Informação, não instrução
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