P0301: Raté de combustion détecté - Cylindre 1
Le code défaut OBD-II P0301 indique que le calculateur de gestion moteur a détecté une absence totale de combustion ou des ratés récurrents localisés spécifiquement sur le cylindre 1. Sur un moteur diesel à rampe commune - dépourvu de système d'allumage commandé -, la détection des ratés est calculée exclusivement par le capteur de position de vilebrequin (capteur PMH/régime moteur) qui mesure les variations sub-microsecondes de la vitesse angulaire du volant moteur. Lorsque la phase de détente du cylindre 1 (30° à 90° après le point mort haut / APMH) produit une chute de décélération de rotation au lieu d'une impulsion d'accélération franchissant le seuil d'étalonnage (généralement > 2,0 % des combustions surveillées), le code P0301 est mémorisé.
🚗 Sécurité d'exploitation, coûts typiques et vérification diagnostique
- 01
🚦 Sécurité de conduite et risque mécanique
Évaluation immédiate et nécessité de remorquageRaté cylindre 1 - Danger de fusion du catalyseur & rinçage du cylindre
Le cylindre 1 a cessé de brûler son carburant, causant de fortes secousses et une chute de couple. RÈGLE CRITIQUE: Voyant moteur FIXE: roulez doucement vers le garage. Voyant moteur CLIGNOTANT: ARRÊTEZ-VOUS IMMÉDIATEMENT! Le carburant imbrûlé enflamme le catalyseur à plus de 1 000 °C (risque d'incendie) et lave le film d'huile sur le cylindre 1 (Cylinder Wash), provoquant le serrage des segments et la perte de compression.
RISQUES MÉCANIQUES EN CAS DE CONDUITE PROLONGÉE :Fusion du nid d'abeilles du catalyseur (1 800 € - 3 500 €), serrage du cylindre 1 par rinçage d'huile (moteur HS à 4 500 €+) et dilution d'huile moteur. - 02
💰 Budget typique de réparation en atelier
Fourchettes de coûts prévues pour pièces et main-d'œuvreEntretien léger / Purge filtre25 € - 95 € (Permutation ou remplacement bougie / bobine cylindre 1)Nettoyage de capteur, remplacement du filtre à carburant, contrôle de fusible ou des connecteurs.
Remplacement vanne / Capteur180 € - 450 € (Décalaminage des soupapes aux coquilles de noix ou nettoyage injecteur GDI)Remplacement d’un composant (régulateur de pression, vanne de dosage ou injecteur reconditionné).
Réfection majeure / Pompe et injecteurs350 € - 1 200 € (Remplacement injecteur direct OEM cylindre 1 avec joint téflon neuf)Révision de pompe haute pression, jeu d’injecteurs neufs ou remplacement de l’ensemble FAP.
- 03
🧰 Vérifications visuelles et simples au garage
Diagnostic rapide en 5 minutes sans outil avant d'appeler le garage1Test d'inversion des bobines 1 et 2: Échangez les bobines entre cylindres 1 et 2. Si le défaut passe en P0302, la bobine est en cause (50 €). Si P0301 persiste, contrôlez l'injecteur et la bougie.2Inspection de la bougie cylindre 1: Démontez la bougie. Si l'électrode est trempée d'essence avec forte odeur, l'injecteur fuit à l'arrêt.3Odeur de carburant sur la jauge d'huile: Si l'huile sent fort l'essence et dépasse le MAX, le carburant imbrûlé a coulé dans le carter. Ne démarrez plus le moteur.4Vérification du joint téflon: Sur moteur GDI, inspectez les traces de suie autour du puits d'injecteur. - 04
🛡️ Bouclier anti-surfacturation mécanicien
Questions précises à poser pour éviter les remplacements inutiles de pièces"Dites au garage: 'J'ai déjà inversé les bobines d'allumage, le raté reste sur le cylindre 1. Ne me facturez pas de diagnostic bobine.'"
"Dites au garage: 'Faites un test de maintien de pression de rampe. Si la pression chute, inspectez le cylindre 1 à l'endoscope pour détecter un injecteur fuyard.'"
"Dites au garage: 'Contrôlez l'encrassement des soupapes d'admission par endoscopie avant de diagnostiquer une perte de compression mécanique.'"
Note technique : Posez ces questions techniques à votre mécanicien avant d'accepter des devis élevés :
Triage atelier en 30 secondes
- Violent engine shaking, severe vibration, and rhythmic thumping at idle (running distinctly on 3 cylinders)
- Flashing or steady Check Engine Light (MIL) on dashboard, accompanied by flashing glow plug light and ESP/traction warning
- Massive loss of engine power, sluggish throttle response, and inability to accelerate up highway gradients
- Completely failed Cylinder 1 fuel injector (blown solenoid coil, seized command piston, or cracked nozzle needle)
- Low mechanical cylinder compression on Cylinder 1 caused by a burnt exhaust valve, broken rocker arm, or holed piston
- Burned-out or heavily carbon-crusted Cylinder 1 glow plug preventing compression ignition during cold ambient starts
Connect scan tool live telemetry: compare Target Fuel Rail Pressure vs Actual Rail Pressure and log metering valve command PWM duty cycle during idle and road load.
Expensive Diagnostic Pitfall & Technical Reality
P0301 proves that Cylinder 1 has suffered catastrophic mechanical valve or piston damage, or that all 4 common rail injectors must be replaced ($1,800 - $3,500).
Diesel engines detect misfires electronically by measuring crankshaft acceleration deceleration via the CKP sensor following Cylinder 1's TDC firing event. In over 80% of verified common rail P0301 cases, cylinder mechanical compression is completely sound. The root failure is typically a blown copper combustion sealing washer allowing compression blowout ('Black Death' tar buildup around injector 1), an injector electrical connector with spread terminal tension caused by engine vibration, or severe hydraulic needle stickiness from fuel lacquer deposits.
Unnecessary engine teardown or replacing all 4 injectors ($2,200+) vs replacing the $3 copper crush washer, re-cutting the seat with a hand reamer ($45 tool), or tensioning connector terminal pins ($0), saving over $2,000.
Moteurs et plateformes d'injection les plus touchés
Ce code défaut affecte principalement les plates-formes diesel à rampe commune suivantes. Consultez votre famille de moteurs pour les causes de panne et références de pièces associées :
Volkswagen / Audi 2.0 TSI EA888 Gen 3 (GTI, Golf R, Audi A4, Q5)
Bosch HDEV5.2 GDI Direct InjectionSymptôme typique : Flashing EPC light under highway passing acceleration, violent cold morning idle shake, raw fuel smell in exhaust.
Mode de défaillance constructeur : Cylinder 1 Bosch multi-hole direct fuel injector sticking closed from carbon varnish or weeping fuel overnight; heavy carbon buildup on Cylinder 1 intake valve tulip.
06L906036K / Bosch 0261500162 (Injector)BMW 2.0T N20 & 3.0T N55 (320i, 328i, 528i, 335i, 535i, X3, X5)
Bosch HDEV5 Solenoid Direct InjectionSymptôme typique : Drivetrain Malfunction message on iDrive, engine misfiring severely on cold morning start, black soot on exhaust tips.
Mode de défaillance constructeur : Cylinder 1 direct injector internal pintle wear allowing pressurized rail fuel to weep into combustion chamber during engine rest, fouling spark plug.
13647597870 / Bosch 0261500109 (Injector)Mercedes-Benz 3.0T & 3.5L V6 M276 (C400, E400, ML350, GL450, S550e)
Bosch Piezo / Solenoid Direct Injection (200 bar)Symptôme typique : Check Engine Light illuminated with severe rough running under heavy towing or kickdown acceleration.
Mode de défaillance constructeur : Cylinder 1 high-pressure fuel injector nozzle tip carbon fouling disrupting spray cone atomization, causing localized lean flameout.
A2760700587 / Bosch 0261500065 (Injector)Honda Civic Type R K20C1 & Accord 2.0T (FK8, FL5)
Keihin Direct Cylinder Injection (200 bar)Symptôme typique : VSA warning lamp and P0301 stored after high-RPM track sessions; rough idle with momentary stumbling.
Mode de défaillance constructeur : Cylinder 1 high-flow direct injector micro-filter screen debris restriction or injector seal ring combustion blow-by.
16450-5BF-A01 / 16010-5BF-305 (Injector)Toyota & Lexus 2.0T 8AR-FTS (IS200t, GS200t, NX200t, RX200t, Crown)
Toyota D-4S Dual Injection (GDI Direct + Port)Symptôme typique : Hesitation during transition from low-speed port injection to high-pressure direct cylinder injection mode.
Mode de défaillance constructeur : Cylinder 1 in-cylinder high-pressure direct injector nozzle tip varnish, leading to poor atomization under high load.
23209-39145 / Denso GDI InjectorCylinder Balance & Injector Deviation Guide
Common rail diesel cylinder balance & smooth running diagnostic guide. Balance rates, mg/stroke deviation, P0263 misfire, compression vs injector test.
Circuit de commande & Logique d'actionneur
1. Dynamic In-Demand Fuel Metering
Diesel compression ignition requires three mandatory physical conditions: high cylinder compression (>22 bar producing air temperatures above 500°C), precise atomization of high-pressure diesel fuel (>250 bar cranking, >1400 bar running), and exact injection timing. The ECM tracks the rotational speed of the flywheel tone ring (60-2 or 36-2). When Cylinder 1 fires correctly, crankshaft rotational speed accelerates sharply. If combustion fails completely (zero heat release), the drag of compressing air causes the crankshaft to slow down rapidly during Cylinder 1's segment, triggering the misfire monitor.
2. Closed-Loop PID Deviation Monitoring
The ECM evaluates misfire data across two independent severity windows: 1. Catalyst / DPF Damaging Window (200 engine revolutions): If the misfire rate is severe enough to allow raw fuel into the exhaust (causing DPF melting), the Check Engine Light flashes violently. 2. Emissions Compliance Window (1,000 engine revolutions): If misfire percentage exceeds 2.0% to 3.0%, a continuous DTC P0301 is logged. The ECM attempts initial compensation by adding fuel via Smooth Running Control (SRC); if the cylinder fails to respond, the ECM cuts fuel to Cylinder 1 to prevent catalytic converter destruction.
3. Diagnostic Trap: Normally Open (NO) vs Normally Closed (NC) Valves
Misfire (P0301) vs Balance Contribution (P0263) Diagnostic Rule: P0263 indicates PARTIAL combustion (the cylinder is running but producing less torque due to coked nozzle holes or minor leakage). P0301 indicates a COMPLETE DEAD MISS: Cylinder 1 has suffered complete combustion failure. In diesel workshops, a dead miss on a single cylinder is caused by one of three primary failures: 1. Complete injector failure (blown solenoid coil, zero fuel injection); 2. Major mechanical compression loss (bent valve, holed piston, broken rocker arm); or 3. Cold-start glow plug burn-out preventing ignition in cold ambient temperatures.
Valeurs de référence électriques & hydrauliques
Protocole de Diagnostic Atelier pas à pas
Injector Cross-Swap Physical Verification (Hardware vs Mechanics)
Remove the Cylinder 1 fuel injector and swap it with Cylinder 2 (using brand-new annealed copper crush washers). Reprogram the respective IMA/QR calibration codes into the ECM via scan tool. Clear trouble codes and start the engine. If the misfire code moves from P0301 to P0302 (Cylinder 2), the injector has an internal mechanical/hydraulic failure: replace it. If the misfire remains stubbornly on Cylinder 1 (P0301), the problem is 100% mechanical (compression/valvetrain) or wiring.
Electronic Relative Compression & Mechanical Gauge Test
Execute an electronic 'Relative Compression Test' via diagnostic scan tool, which monitors starter current draw and crankshaft angular speed across each cylinder's compression stroke. If Cylinder 1 shows <85% relative compression, remove the Cylinder 1 glow plug and thread in a physical diesel mechanical compression gauge. Crank engine: compression must exceed 22 bar (320 psi) with <3 bar variance to companion cylinders. A reading below 18 bar confirms blown piston rings, burnt valves, or a blown head gasket.
Individual Injector Backleak (Return Flow) Measurement
Disconnect the low-pressure fuel return lines from all injectors. Attach graduated transparent test tubes to the return nipples. Crank the engine for 15 seconds (or run at warm idle for 2 minutes). A healthy injector returns less than 20-25 mL at idle. If Cylinder 1 returns excessive fuel (>40 mL) or fills the bottle instantly during cranking, its internal control valve has collapsed, dumping rail pressure and preventing the needle from lifting.
Injector Solenoid Coil Resistance & 250V Megohmmeter Test
Disconnect the Cylinder 1 injector harness. Using a precision digital multimeter on the 200 Ω scale, measure coil resistance: solenoid injectors must measure 0.20 Ω to 0.45 Ω @ 20°C; piezo injectors must measure 180 kΩ to 220 kΩ. Next, test insulation resistance to the metal body with an automotive insulation tester set to 250V/500V test voltage (must exceed >10 MΩ). A low reading confirms high-voltage dielectric breakdown arcing into the cylinder head.
Glow Plug Resistance & Power Feed Audit (Cold Start Misfires)
If the P0301 misfire occurs exclusively during the first 3 to 5 minutes following a cold start, disconnect the Cylinder 1 glow plug lead. Measure resistance between the glow plug center terminal and engine cylinder block ground. A healthy glow plug measures 0.4 Ω to 1.2 Ω. An open circuit (infinite resistance / OL) confirms a burned-out glow plug that leaves Cylinder 1 too cold to ignite diesel.
Cylinder 1 Valvetrain & Camshaft Lobe Inspection
Remove the engine valve/camshaft cover. Visually inspect the intake and exhaust camshaft lobes and roller rocker arms for Cylinder 1. Look for worn, flattened camshaft lobes (very common on high-mileage VAG TDI and Ford engines) or collapsed hydraulic lash adjusters. A flattened intake cam lobe prevents the intake valves from opening fully, starving the cylinder of oxygen.
Réparation matérielle & Nomenclature sous-ensembles
Isolate localized ignition, intake valve carbon coking, and direct injector weeping before replacing major engine assemblies:
0261500162 / 06L906036KBosch
OEM multi-hole high-pressure direct fuel injector. Restores optimal conical spray geometry and eliminates Cylinder 1 misfire.
0261500109 / 13647597870Bosch
Original factory solenoid direct fuel injector. Cures cold morning cylinder wash and persistent Cylinder 1 misfire stumble.
0261500065 / A2760700587Bosch
High-precision CGI direct fuel injector assembly for Mercedes BiTurbo V6 platforms. Eliminates high-load misfires.
16450-5BF-A01 / 16010-5BF-305Keihin
OEM factory high-flow direct injector. Resolves high-RPM fuel starvation and Cylinder 1 combustion cut.
23209-39145 / 23209-31105Denso
Original equipment direct-in-cylinder fuel injector with Teflon seal ring for D-4S twin-injection platforms.
Calculateur dynamique de tolérances Common Rail
Composants d'injection associés
Les pompes à carburant et injecteurs à rampe commune d'origine suivants sont vérifiés pour les moteurs signalant le code P0301. Vérifiez les pressions de service avant le remplacement :
095000-5880Denso
095000-5880 Denso Toyota 2KD-FTV Injector: 23670-30050 Data
View Technical Specs & Fitment →28337917Delphi
28337917 Delphi Bobcat D24 Injector: 7030364 Specs & Data
View Technical Specs & Fitment →095000-8340Denso
095000-8340 Denso Mitsubishi 4D56 HP Injector: 1465A367 Data
View Technical Specs & Fitment →0445120289Bosch
0445120289 Bosch Perkins 1104D Injector: 2645A749 Data
View Technical Specs & Fitment →0445120357Bosch
0445120357 Bosch Cummins ISDe 6.7L Injector: 4988835 Data
View Technical Specs & Fitment →0445110594Bosch
0445110594 Bosch VW 1.6 TDI Injector: 03L130277S Data
View Technical Specs & Fitment →Réinitialisation de la pompe HP & Cycle d'apprentissage
Following replacement of the Cylinder 1 fuel injector, glow plug, or cylinder head servicing, execute the adaptation routine:
1. Enter the new 6-to-30 digit alphanumeric calibration code (IMA/QR code) stamped on the top of the new Cylinder 1 injector into the ECM via scan tool.
2. Clear all stored diagnostic trouble codes and confirm engine coolant temperature is above 75°C (167°F).
3. Access scan tool 'Engine Control Module' -> 'Special Functions' -> select 'Reset Cylinder Balance / Smooth Running Values'.
4. Start the engine and allow it to idle undisturbed in park/neutral for 5 minutes without touching any pedals, allowing the ECM to build initial torque offsets.
5. Accelerate vehicle smoothly in 4th gear to 80 km/h (2200 RPM), then release throttle completely to coast down in gear to 35 km/h (minimum 8s overrun).
6. Repeat this acceleration and coast-down sequence 5 times. Return to workshop and confirm Cylinder 1 misfire counter remains at absolute zero.
Diagnostic différentiel & Codes associés
Random or Multiple Cylinder Misfire Detected
Multi-cylinder misfire code triggered when systemic issues (air in fuel, bad fuel, low rail pressure) cause misfiring across multiple cylinders.
Cylinder 1 Contribution/Balance Fault
Milder predecessor fault indicating Cylinder 1 is producing degraded torque; if contribution degrades further into complete flameout, P0301 triggers.
Injector Circuit/Open - Cylinder 1
Electrical circuit fault code on Cylinder 1; if an injector wiring open/short develops, P0201 will trigger alongside or override P0301.
Cas pratiques d'atelier
2014 Mercedes-Benz C220 CDI (W204 OM651)(185,000 km)
Questions techniques fréquentes
Que signifie le code défaut P0301 ?
Le code défaut OBD-II P0301 indique que le calculateur de gestion moteur a détecté une absence totale de combustion ou des ratés récurrents localisés spécifiquement sur le cylindre 1. Sur un moteur diesel à rampe commune - dépourvu de système d'allumage commandé -, la détection des ratés est calculée exclusivement par le capteur de position de vilebrequin (capteur PMH/régime moteur) qui mesure les variations sub-microsecondes de la vitesse angulaire du volant moteur. Lorsque la phase de détente du cylindre 1 (30° à 90° après le point mort haut / APMH) produit une chute de décélération de rotation au lieu d'une impulsion d'accélération franchissant le seuil d'étalonnage (généralement > 2,0 % des combustions surveillées), le code P0301 est mémorisé.
Quels sont les symptômes les plus fréquents de P0301 ?
Violent engine shaking, severe vibration, and rhythmic thumping at idle (running distinctly on 3 cylinders), Flashing or steady Check Engine Light (MIL) on dashboard, accompanied by flashing glow plug light and ESP/traction warning, Massive loss of engine power, sluggish throttle response, and inability to accelerate up highway gradients, Dense clouds of white or blue-grey exhaust smoke on cold start (raw unburned atomized diesel fuel vapor), Overwhelming raw diesel exhaust odor noticeable around the vehicle and through cabin air vents, Scan tool live data shows Cylinder 1 misfire counter incrementing rapidly (>50 counts per 1000 revolutions).
Quelles sont les causes de P0301 sur un diesel ?
Completely failed Cylinder 1 fuel injector (blown solenoid coil, seized command piston, or cracked nozzle needle); Low mechanical cylinder compression on Cylinder 1 caused by a burnt exhaust valve, broken rocker arm, or holed piston; Burned-out or heavily carbon-crusted Cylinder 1 glow plug preventing compression ignition during cold ambient starts; Broken, corroded, or shorted wiring harness wire between the ECM and the Cylinder 1 fuel injector connector; Internal low-side power MOSFET driver transistor failure for Cylinder 1 inside the Engine Control Module (ECM); Intake valve carbon choking or stuck-shut intake swirl flap starving Cylinder 1 of necessary fresh air charge.
Est-il prudent de rouler avec le code P0301 actif ?
🟡 Attention : Mode dégradé actif / Réparation requise
Combien coûte la réparation du code défaut P0301 ?
Le coût moyen de réparation du code défaut P0301 dépend de la cause racine et du niveau de diagnostic : Niveau 1 (Entretien mineur / DIY) : 25 € - 95 € (Permutation ou remplacement bougie / bobine cylindre 1) (Nettoyage de capteur, remplacement du filtre à carburant, contrôle de fusible ou des connecteurs.); Niveau 2 (Remplacement composant) : 180 € - 450 € (Décalaminage des soupapes aux coquilles de noix ou nettoyage injecteur GDI) (Remplacement d’un composant (régulateur de pression, vanne de dosage ou injecteur reconditionné).); Niveau 3 (Sous-ensemble complet) : 350 € - 1 200 € (Remplacement injecteur direct OEM cylindre 1 avec joint téflon neuf) (Révision de pompe haute pression, jeu d’injecteurs neufs ou remplacement de l’ensemble FAP.). Tarifs indicatifs d’atelier. Les données indiquent que plus de 70% des cas sont résolus aux niveaux 1 ou 2 sans remplacer les sous-ensembles complets.
Can a bad glow plug cause code P0301 in a diesel engine?
Yes, but specifically during cold starts and the first 3 to 5 minutes of engine warm-up. Unlike gasoline spark plugs which fire continuously, diesel glow plugs only operate during pre-glow and post-glow phases to keep cold cylinder walls warm. If the Cylinder 1 glow plug is burned out, cold compression cannot reach the 500°C auto-ignition temperature of diesel, causing Cylinder 1 to misfire (P0301) and puff white unburned fuel smoke until the cylinder block heats up.
Why does my diesel car misfire on Cylinder 1 under heavy load but idle fine?
At idle, common rail fuel pressure is only 250 to 350 bar, and the injector needs to deliver only a tiny 5 mg micro-pulse. Under full load, rail pressure spikes to 1800+ bar and fuel delivery increases tenfold. If the Cylinder 1 injector has internal control valve wear (excessive backleak) or a partially clogged nozzle, it can deliver enough fuel at low pressure to idle smoothly, but completely fails to deliver the massive volume demanded at 1800 bar, dropping cylinder torque and triggering P0301.
What is the fastest way to confirm whether the Cylinder 1 injector is bad?
The most reliable test is the physical cross-swap. Remove the Cylinder 1 injector and swap it with Cylinder 2 (always install new annealed copper seating washers). Enter the calibration codes into the scan tool and drive the vehicle. If the misfire moves to Cylinder 2 (P0302), you have 100% proven the injector is defective. If the misfire stays on Cylinder 1 (P0301), you know the injector is innocent and must check mechanical cylinder compression.