P0400 means the engine control unit has detected that exhaust gas recirculation flow is not within the expected range. The EGR system recirculates a portion of exhaust gas back into the intake to lower combustion temperatures and reduce NOx emissions. A blockage or valve failure disrupts this flow.
P0400 means the engine control unit has detected that exhaust gas recirculation flow is not within the expected range. The EGR system recirculates a portion of exhaust gas back into the intake to lower combustion temperatures and reduce NOx emissions. A blockage or valve failure disrupts this flow.
P0400 est un code defaut lie a emissions, classe en gravite moderate. Lorsque le calculateur de ton vehicule detecte cette condition, il enregistre P0400 et allume le voyant moteur.
Si ton vehicule a declenche P0400, tu peux remarquer un ou plusieurs de ces symptomes :
Voici les causes les plus courantes de P0400, classees selon la probabilite qu'elles soient en cause :
En general oui, pour des trajets courts. The vehicle is generally safe to drive in the short term, but EGR faults can cause increased NOx emissions, rough idle, and reduced fuel economy. Repair before the next emissions inspection.
Suis ces etapes pour identifier la cause profonde de P0400 :
Les couts de reparation de P0400 varient selon la cause profonde et ton vehicule. Voici des estimations courantes :
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
P0400 se comporte differemment selon ton vehicule. Selectionne ta voiture ci-dessous pour des causes propres au modele, les problemes connus et des estimations de couts ajustees :
2003-2024
The 1.9 TDI and 2.0 TDI engines are well-known for EGR valve carbon clogging, especially in stop-and-go city driving. The EGR cooler on the 2.0 TDI (CR) can also crack, leading to coolant loss. Regular motorway driving helps keep the EGR cleaner.
Couts estimes pour les proprietaires de Volkswagen Golfajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Volkswagen
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2005-2022
The 1.6 TDCi engine uses a vacuum-actuated EGR valve that is prone to carbon buildup and diaphragm failure. The DPFE (differential pressure feedback) sensor on the 2.0 Duratec petrol engine is a known failure point and is inexpensive to replace.
2004-2024
The 1.7 CDTi (Z17DTH/A17DTJ) is very susceptible to EGR clogging, particularly in urban driving. The EGR valve on these engines is electrically operated and can seize in the open position, causing rough idle and excessive smoke.
2007-2024
The 1.6 HDi (DV6) engine shares its EGR system with the Ford 1.6 TDCi and is equally prone to carbon clogging. The 2.0 HDi has a more robust EGR setup but the cooler can develop leaks after 100,000 km.
Couts estimes pour les proprietaires de Peugeot 308ajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Peugeot
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
Ces codes apparaissent souvent avec P0400 ou indiquent des problemes connexes :
The Exhaust Gas Recirculation system routes a small amount of exhaust gas back into the engine intake. This lowers combustion temperatures and significantly reduces nitrogen oxide (NOx) emissions, which are a major component of smog.
Yes, for a short time. The vehicle will run, but you may notice rough idle, knocking under load, and poor fuel economy. The main risk is failing an emissions test and potentially causing increased engine wear from higher combustion temperatures.
On diesel engines, EGR cleaning every 40,000 to 60,000 km is advisable due to higher soot levels. Petrol engines accumulate carbon more slowly, but a cleaning every 80,000 to 100,000 km is good preventive maintenance.
P0400 is a general EGR flow malfunction, meaning the flow is outside the expected range. P0401 specifically means insufficient EGR flow, which is usually caused by a clogged valve or blocked passage. P0400 is less specific about the direction of the fault.
In the EU, blocking or deleting the EGR system is illegal and will cause the vehicle to fail its periodic roadworthiness test (TUV, MOT, ITV, etc.). It also significantly increases NOx emissions. The correct approach is to clean or replace the faulty component.
Une vanne EGR défectueuse donne un ralenti instable, des à-coups et un code P0401. Voici son rôle, les symptômes bloquée ouverte ou fermée, et le coût.
Fixing P0401 starts with cleaning the EGR valve, under 20 euros if you do it yourself. Replacement runs 160-550 euros. Here is how to know which one you need.
Branche un adaptateur OBD2 Bluetooth standard, scanne les codes et obtiens un diagnostic par IA avec niveaux de gravite et estimations des couts de reparation.
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