P0404 means the EGR valve is responding to ECU commands, but not within the expected position range. The ECU asks for a specific opening (say 30%) and the position sensor reports something different. Carbon buildup restricting valve travel is by far the most common cause.
P0404 means the EGR valve is responding to ECU commands, but not within the expected position range. The ECU asks for a specific opening (say 30%) and the position sensor reports something different. Carbon buildup restricting valve travel is by far the most common cause.
P0404 è un codice diagnostico di guasto relativo a emissioni, classificato con gravità moderate. Quando la centralina (ECU) del tuo veicolo rileva questa condizione, memorizza P0404 e accende la spia motore.
Se il tuo veicolo ha attivato P0404, potresti notare uno o più di questi sintomi:
Ecco le cause più comuni di P0404, ordinate in base alla probabilità che siano la causa del problema:
In genere sì, per brevi tragitti. Driveable. P0404 means the EGR valve is moving, but its actual position does not match what the ECU commanded. Expect rough idle, possible hesitation, and a failed emissions test. Some diesels limit power to protect the DPF and SCR systems.
Segui questi passaggi per individuare la causa principale di P0404:
I costi di riparazione di P0404 variano a seconda della causa principale e del tuo veicolo. Ecco le stime tipiche:
Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.
P0404 si comporta in modo diverso a seconda del tuo veicolo. Seleziona la tua auto qui sotto per cause specifiche del modello, problemi noti e stime dei costi adeguate:
2007–2024
On the N47 and B47 320d, P0404 typically appears around 100,000–130,000 km as carbon accumulates at the EGR valve seat and limits pintle travel. The position sensor reports the valve isn't reaching commanded angles. Cleaning sometimes works, but on chronically affected engines the EGR cooler-valve assembly is replaced as a unit since they are sold together. EGR adaptation must be reset with INPA, ISTA, or Carly after the job.
Costi stimati per i proprietari di BMW 3 Seriesadeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici BMW
Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.
2009–2024
EA189 and EA288 Golf TDIs throw P0404 frequently after the Dieselgate update because the new EGR strategy demands wider valve travel. The pintle reaches limit positions where carbon prevents it from closing fully. VCDS can read the position sensor in measured value blocks (group 99 on EA189, group 144 on EA288) to confirm. Adaptation reset via VCDS is required after any valve service.
Costi stimati per i proprietari di Volkswagen Golfadeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Volkswagen
Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.
2008–2024
The A4 2.0 TDI (B8, B9) shares the EA189 and EA288 EGR setup with the Golf, so P0404 has identical root causes. The 3.0 TDI V6 (CCWA, CTBA codes) uses a more complex dual-bank EGR with separate position sensors per bank, and adaptation must be performed for both sides after service. VCDS or ODIS is required.
Costi stimati per i proprietari di Audi A4adeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Audi
Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.
2010–2024
OM651 Sprinters often see P0404 alongside P0401 due to heavy commercial duty cycles. The position sensor on the OM651 EGR valve is integrated and not serviceable separately. When the sensor drifts or the pintle sticks, replacement of the complete valve is required, plus Star Diagnosis or XENTRY for the adaptation reset. Skipping the adaptation will cause the code to return.
Costi stimati per i proprietari di Mercedes Sprinteradeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Mercedes-Benz
Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.
Questi codici compaiono spesso insieme a P0404 o indicano problemi correlati:
P0403 is a pure electrical circuit fault (open, short, no response). P0404 means the circuit works, but the valve position does not match the commanded position. P0404 is almost always mechanical (carbon buildup, sticking pintle), while P0403 is usually electrical (solenoid, wiring, connector).
Yes, short-term. Some modern diesels go into limp mode if the EGR cannot reach commanded positions, because the after-treatment calibration relies on EGR for NOx control. Plan the repair within a few weeks to avoid secondary DPF or SCR codes.
On petrol engines, often yes if you also clean the intake manifold passages. On diesels with heavy soot output (BMW N47/B47, VAG EA189), cleaning may only last 20,000–40,000 km before the code returns. If the EGR cooler is degraded, replacement of the cooler-valve assembly is more durable.
Yes on most modern vehicles. BMW, Mercedes, and VAG all use stored adaptation values that must be reset and re-learned after a new EGR valve is fitted. INPA, VCDS, or a similar bi-directional scan tool is required. Skipping this step often causes the new valve to throw P0404 again within a few drive cycles.
EGR deletion is the hardest of the three diesel emissions cheats to detect with OBD2. Here is what the scan tool reveals, what it cannot, and three physical checks that close the gap.
M57 vs M57N vs M57N2 across E60/E61. Swirl flap delete, twin-turbo wastegate on the 535d, ZF 6HP mechatronic. Five OBD2 checks before 3,000-12,000 EUR.
1.9 PD vs 2.0 TDI CR EA189 vs EA288 across Mk5/6/7/8. Dieselgate fix legacy, DSG mechatronic, DPF on short trips. Five OBD2 checks before 5,000-22,000 EUR.
OM651 balance shaft wear, injector failures, AdBlue countdown, DPF on stop-start duty. The 5 OBD2 checks before you pay 8,000-45,000 EUR for a used Sprinter.
Collega un adattatore OBD2 Bluetooth standard, esegui la scansione dei codici e ottieni una diagnosi basata sull'IA con livelli di gravità e stime dei costi di riparazione.
Scarica Skanyx