P0402 means the EGR system is flowing too much exhaust gas back into the intake manifold. The most common cause is an EGR valve stuck partially open, often due to carbon buildup on the valve seat. Diesel engines are especially vulnerable because of higher soot output.
P0402 means the EGR system is flowing too much exhaust gas back into the intake manifold. The most common cause is an EGR valve stuck partially open, often due to carbon buildup on the valve seat. Diesel engines are especially vulnerable because of higher soot output.
P0402 est un code defaut lie a emissions, classe en gravite moderate. Lorsque le calculateur de ton vehicule detecte cette condition, il enregistre P0402 et allume le voyant moteur.
Si ton vehicule a declenche P0402, tu peux remarquer un ou plusieurs de ces symptomes :
Voici les causes les plus courantes de P0402, classees selon la probabilite qu'elles soient en cause :
En general oui, pour des trajets courts. Driveable short-term, but excessive EGR flow causes rough idle, hesitation, and may stall the engine at low RPM. Extended driving with excess EGR contaminates the intake and accelerates carbon buildup on intake valves (especially direct-injection engines). Get it fixed before next emissions test.
Suis ces etapes pour identifier la cause profonde de P0402 :
Les couts de reparation de P0402 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.
P0402 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 :
2007–2024
The 320d with N47 and later B47 engines is notorious for EGR-related faults. Carbon buildup at the EGR valve seat is virtually guaranteed past 120,000 km, and the EGR cooler often cracks internally, leaking coolant into the exhaust stream. When P0402 appears alongside P0401 or low-coolant warnings, suspect cooler failure. BMW issued recall campaigns in several EU markets for N47/B47 EGR cooler fires.
Couts estimes pour les proprietaires de BMW 3 Seriesajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a BMW
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2009–2024
Golf TDI models with the EA189 (pre-Dieselgate) and EA288 (post-fix) engines commonly throw P0402 after the emissions software update was applied. The remapped EGR strategy runs the valve at higher duty cycles, which accelerates carbon buildup at the seat. Cleaning the valve and intake manifold passages restores normal operation. On 1.4 TSI petrol Golfs, the integrated EGR cooler in the exhaust manifold can also stick open.
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.
2008–2024
The A4 2.0 TDI (B8 and B9 chassis) shares EA189 and EA288 engines with the Golf and suffers identical EGR carbon issues. The valve is harder to access on the A4 due to tighter engine bay packaging, which pushes labor costs higher. On 3.0 TDI V6 models, the dual EGR coolers add complexity and parts cost when failure occurs.
Couts estimes pour les proprietaires de Audi A4ajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Audi
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2010–2024
Sprinter vans with the OM651 2.1 CDI engine are heavy commercial users that see EGR faults early due to high duty cycles and frequent low-load city driving. The EGR cooler interacts with the AdBlue (SCR) system, so a stuck-open EGR valve often pulls down NOx sensor readings and triggers AdBlue limp-mode countdown. Cleaning is rarely a long-term fix on commercial Sprinters, replacement is more common.
Couts estimes pour les proprietaires de Mercedes Sprinterajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Mercedes-Benz
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
Ces codes apparaissent souvent avec P0402 ou indiquent des problemes connexes :
Short distances yes, but expect rough idle and possible stalling. Excessive EGR flow dumps soot and exhaust into the intake, which accelerates carbon buildup on intake valves, especially on direct-injection engines. Get it diagnosed within a few weeks.
No. EGR delete is illegal across the EU and UK. It increases NOx emissions, triggers a permanent check engine light, fails the periodic technical inspection (TÜV in Germany, ITV in Spain, TA in Lithuania, SKP in Poland), and can result in vehicle deregistration. Stick to cleaning or replacement.
Often yes. P0402 is usually caused by carbon stopping the valve from closing fully. Removing the valve, soaking it in EGR cleaner or carb cleaner, and clearing the seat resolves the code on roughly half of cases. If the solenoid or motor itself has failed, replacement is needed.
Diesel engines produce far more soot than petrol, so the EGR valve re-fouls quickly. If the EGR cooler is also blocked or leaking internally, the valve will stick open again within months. On heavily affected engines (BMW N47, M57), the cooler often needs replacement alongside the valve.
An EGR valve clean runs 80 to 200 euros, a full replacement 150 to 600. Here is what each costs on a 1.6 and 2.0 TDI, and when carbon means clean over replace.
Clean a carboned diesel EGR valve yourself for €10-30. Symptoms, step-by-step removal, when to clean vs replace, and how to verify the fix with OBD2.
Your car dies at every red light, then restarts fine. Here is what causes a car to shut off when you stop, how to find the fault, and what fixes cost.
A 210,000 km imported diesel that looks too clean hides its faults in the OBD2 data. Here are the red flags a scan catches before you wire the money.
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.
Telecharger Skanyx