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DTC/P0305

P0305: Cylinder 5 Misfire Detected

Quick Answer
Alta GravitàNon sicuro da guidareMancata accensione

P0305 means the ECU counted enough missed combustion events on cylinder 5 (typically over 2% of firings in a 200-rev window) to trip the misfire monitor. Expect rough running and a flashing CEL under load.

Costo di riparazione stimatoDa €45 a €2700+, varia in base al veicolo

Scansiona la tua auto in circa 60 secondi: scopri se P0305 è davvero presente, quanto è urgente e quanto dovrebbe costare la riparazione.

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Cosa significa P0305?

P0305 means the ECU counted enough missed combustion events on cylinder 5 (typically over 2% of firings in a 200-rev window) to trip the misfire monitor. Expect rough running and a flashing CEL under load.

P0305 è un codice diagnostico di guasto relativo a mancata accensione, classificato con gravità high. Quando la centralina (ECU) del tuo veicolo rileva questa condizione, memorizza P0305 e accende la spia motore.

Quali sono i sintomi di P0305?

Se il tuo veicolo ha attivato P0305, potresti notare uno o più di questi sintomi:

  • Rough idle with a noticeable shake through the steering wheel
  • Flashing check engine light during acceleration or under load
  • Loss of power, especially uphill or when merging
  • Fuel economy drop of roughly 5-15% depending on how often the cylinder drops out
  • Exhaust popping or hesitation on throttle tip-in
  • Raw fuel smell from the tailpipe at idle
  • Long fuel trims skewed on the bank containing cylinder 5

Cosa causa P0305?

Ecco le cause più comuni di P0305:

altaWorn or fouled spark plug on cylinder 5
altaFailed coil-on-plug or coil pack feeding cylinder 5
mediaClogged or electrically failed fuel injector on cylinder 5
mediaVacuum leak at the intake runner, injector O-ring, or PCV hose near cylinder 5
bassaLow compression from burnt exhaust valve or worn rings
bassaBroken valve spring, collapsed lifter, or timing chain stretch

È sicuro guidare con P0305?

No, risolvi subito il problema. You can limp home, but a sustained misfire dumps raw fuel into the catalytic converter and can destroy it within a tank or two. Fix it before your next commute.

Come si diagnostica P0305?

Segui questi passaggi per individuare la causa principale di P0305:

  1. Read all stored and pending codes. Note fuel trims and any lean/rich codes (P0171, P0174) that could point at a vacuum or injector issue.
  2. Pull the coil and plug from cylinder 5. Fouled electrode, cracked insulator, or oil in the plug well tells you a lot before you swap anything.
  3. Swap the cylinder 5 coil with a neighbouring cylinder, clear codes, and drive. If the code moves (e.g. becomes P0303), replace the coil.
  4. Swap the injector connector or the injector itself with a neighbour if the coil swap didn't move the misfire. A noid light confirms the ECU is pulsing the injector.
  5. Check live fuel trims and misfire counters with a scan tool. Positive trim on the affected bank points to vacuum leak or weak injector flow.
  6. Smoke-test the intake if trims are lean. Cracked PCV hoses and split intake boots are common culprits.
  7. Compression test cylinder 5. More than 15% below the average of the other cylinders points to mechanical trouble. Follow up with a leakdown to isolate valves vs rings.
  8. After repair, clear codes and complete a misfire monitor drive cycle before declaring victory.

Quanto costa riparare P0305?

I costi di riparazione di P0305 variano a seconda della causa principale e del tuo veicolo. Ecco le stime tipiche:

Riparazione Costo dei ricambi Costo della manodopera Stima totale Difficoltà fai-da-te
Replace spark plug on cylinder 5 (usually do the full set) €15–€80 €30–€120 €45–€200 Facile
Replace ignition coil on cylinder 5 €40–€180 €30–€90 €70–€270 Facile
Replace or ultrasonically clean fuel injector on cylinder 5 €80–€350 €100–€300 €180–€650 Moderata
Intake manifold gasket replacement to fix a vacuum leak €40–€150 €150–€400 €190–€550 Moderata
Cylinder head work after failed compression/leakdown (valve job or head R&R) €300–€1200 €400–€1500 €700–€2700 Professionale

Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.

P0305 su veicoli specifici

P0305 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:

Ford

P0305 su Ford F-150 5.4L Triton 3V

2004-2010

The 3-valve 5.4L Triton is covered by Ford TSB 08-7-6 for coil-on-plug failures and the two-piece spark plug design that shears off in the head. Cylinder 5 is passenger-side rear and typically fails first.

Cosa causa P0305 su una Ford F-150 5.4L Triton 3V?

Ford F-150 5.4L Triton 3VMotorcraft DG-511 coil boot cracking and arcing to the valve cover
Ford F-150 5.4L Triton 3VTwo-piece plug breaking on removal (budget for a Lisle 65600 extractor)
Ford F-150 5.4L Triton 3VCam phaser wear causing timing-related misfire under load

Costo di riparazione di P0305 per Ford F-150 5.4L Triton 3V

Costi stimati per i proprietari di Ford F-150 5.4L Triton 3Vadeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Ford

Riparazione Costo dei ricambi Costo della manodopera Stima totale Difficoltà fai-da-te
Replace spark plug on cylinder 5 (usually do the full set) €18–€96 €36–€144 €54–€240 Facile
Replace ignition coil on cylinder 5 €48–€216 €36–€108 €84–€324 Facile
Replace or ultrasonically clean fuel injector on cylinder 5 €96–€420 €120–€360 €216–€780 Moderata
Intake manifold gasket replacement to fix a vacuum leak €48–€180 €180–€480 €228–€660 Moderata
Cylinder head work after failed compression/leakdown (valve job or head R&R) €360–€1440 €480–€1800 €840–€3240 Professionale

Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.

BMW

P0305 su BMW 3-Series E90/E92 (N54, N55)

2007-2013

N54 and N55 inline-sixes chew through Bosch coils and NGK index plugs. N54 injectors were covered by an extended warranty (10 years/120,000 miles (190,000 km) in the US) for exactly this failure mode.

Cosa causa P0305 su una BMW 3-Series E90/E92 (N54, N55)?

BMW 3-Series E90/E92 (N54, N55)Bosch coil pack failure (replace as a matched set of 6)
BMW 3-Series E90/E92 (N54, N55)N54 piezo injector failure causing lean misfire (recall/extended warranty items)
BMW 3-Series E90/E92 (N54, N55)HPFP weakness dropping rail pressure under load on N54

Costo di riparazione di P0305 per BMW 3-Series E90/E92 (N54, N55)

Costi stimati per i proprietari di BMW 3-Series E90/E92 (N54, N55)adeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici BMW

Riparazione Costo dei ricambi Costo della manodopera Stima totale Difficoltà fai-da-te
Replace spark plug on cylinder 5 (usually do the full set) €21–€112 €42–€168 €63–€280 Facile
Replace ignition coil on cylinder 5 €56–€252 €42–€126 €98–€378 Facile
Replace or ultrasonically clean fuel injector on cylinder 5 €112–€490 €140–€420 €252–€910 Moderata
Intake manifold gasket replacement to fix a vacuum leak €56–€210 €210–€560 €266–€770 Moderata
Cylinder head work after failed compression/leakdown (valve job or head R&R) €420–€1680 €560–€2100 €980–€3780 Professionale

Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.

Toyota

P0305 su Toyota Camry 3.5L V6 (2GR-FE)

2007-2017

Cylinder 5 lives on the rear bank against the firewall. The upper intake plenum has to come off for proper coil and plug access, which is why shop labour runs high on this job.

Cosa causa P0305 su una Toyota Camry 3.5L V6 (2GR-FE)?

Toyota Camry 3.5L V6 (2GR-FE)Denso coil failure past 150,000 km, often one at a time
Toyota Camry 3.5L V6 (2GR-FE)VVT-i oil control valve fault causing timing-linked misfire
Toyota Camry 3.5L V6 (2GR-FE)Water pump seepage dripping onto the rear bank harness (2GR-FE known issue)

Costo di riparazione di P0305 per Toyota Camry 3.5L V6 (2GR-FE)

Costi stimati per i proprietari di Toyota Camry 3.5L V6 (2GR-FE)adeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Toyota

Riparazione Costo dei ricambi Costo della manodopera Stima totale Difficoltà fai-da-te
Replace spark plug on cylinder 5 (usually do the full set) €17–€88 €33–€132 €50–€220 Facile
Replace ignition coil on cylinder 5 €44–€198 €33–€99 €77–€297 Facile
Replace or ultrasonically clean fuel injector on cylinder 5 €88–€385 €110–€330 €198–€715 Moderata
Intake manifold gasket replacement to fix a vacuum leak €44–€165 €165–€440 €209–€605 Moderata
Cylinder head work after failed compression/leakdown (valve job or head R&R) €330–€1320 €440–€1650 €770–€2970 Professionale

Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.

Volkswagen

P0305 su VW Golf R32 3.2L VR6 (BUB)

2004-2008

The narrow-angle VR6 uses six individual coil packs on a single head. Original brown coils (VW p/n 06B905115) were superseded by updated units after widespread failures.

Cosa causa P0305 su una VW Golf R32 3.2L VR6 (BUB)?

VW Golf R32 3.2L VR6 (BUB)Original brown coil pack failure (update to later black/red version)
VW Golf R32 3.2L VR6 (BUB)Coil harness connector corrosion from engine bay water intrusion
VW Golf R32 3.2L VR6 (BUB)Timing chain tensioner wear on high-mileage examples retarding cam timing

Costo di riparazione di P0305 per VW Golf R32 3.2L VR6 (BUB)

Costi stimati per i proprietari di VW Golf R32 3.2L VR6 (BUB)adeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Volkswagen

Riparazione Costo dei ricambi Costo della manodopera Stima totale Difficoltà fai-da-te
Replace spark plug on cylinder 5 (usually do the full set) €19–€100 €38–€150 €56–€250 Facile
Replace ignition coil on cylinder 5 €50–€225 €38–€113 €88–€338 Facile
Replace or ultrasonically clean fuel injector on cylinder 5 €100–€438 €125–€375 €225–€813 Moderata
Intake manifold gasket replacement to fix a vacuum leak €50–€188 €188–€500 €238–€688 Moderata
Cylinder head work after failed compression/leakdown (valve job or head R&R) €375–€1500 €500–€1875 €875–€3375 Professionale

Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.

Jeep

P0305 su Jeep Grand Cherokee 5.7L HEMI

2005-2018

The HEMI runs 16 plugs (two per cylinder). MDS cylinder deactivation applies to cylinders 1, 4, 6 and 7, so on cylinder 5 a persistent misfire is almost always coil, plug, or a collapsed lifter rather than an MDS fault.

Cosa causa P0305 su una Jeep Grand Cherokee 5.7L HEMI?

Jeep Grand Cherokee 5.7L HEMIOne of the two plugs on cylinder 5 fouled while the other reads fine
Jeep Grand Cherokee 5.7L HEMICollapsed roller lifter wiping the cam lobe (common HEMI failure)
Jeep Grand Cherokee 5.7L HEMIExhaust manifold bolt breakage causing a localised leak that trips the misfire monitor

Costo di riparazione di P0305 per Jeep Grand Cherokee 5.7L HEMI

Costi stimati per i proprietari di Jeep Grand Cherokee 5.7L HEMIadeguato al rialzo rispetto alla media a causa dei prezzi dei ricambi specifici Jeep

Riparazione Costo dei ricambi Costo della manodopera Stima totale Difficoltà fai-da-te
Replace spark plug on cylinder 5 (usually do the full set) €20–€104 €39–€156 €59–€260 Facile
Replace ignition coil on cylinder 5 €52–€234 €39–€117 €91–€351 Facile
Replace or ultrasonically clean fuel injector on cylinder 5 €104–€455 €130–€390 €234–€845 Moderata
Intake manifold gasket replacement to fix a vacuum leak €52–€195 €195–€520 €247–€715 Moderata
Cylinder head work after failed compression/leakdown (valve job or head R&R) €390–€1560 €520–€1950 €910–€3510 Professionale

Prezzi stimati al March 2026. I costi variano in base alla regione, al veicolo e all'officina.

Questi codici compaiono spesso insieme a P0305 o indicano problemi correlati:

Domande frequenti su P0305

Can I swap the cylinder 5 coil with another cylinder to test it?

Yes, and it's the fastest free test you can do. Move the cylinder 5 coil to cylinder 1 or 3, clear the code, and drive. If P0301 or P0303 pops, the coil is bad. If P0305 comes back, the coil is fine and you're looking at plug, injector, or mechanical.

Will driving with P0305 kill my catalytic converter?

Yes, and quickly. A flashing CEL means raw fuel is hitting a red-hot cat. A sustained misfire can destroy a converter in a few hundred kilometres, turning an €80 coil job into a €600-€1500 cat replacement.

Why does cylinder 5 fail more often than other cylinders?

On most transverse V6s and longitudinal V8s, cylinder 5 sits at the rear of the head where heat soak from the firewall or exhaust is worst. Coils cook faster there. On inline sixes it's simply the second-hottest position. It's not random - rear cylinders live a harder life.

The misfire only happens when the engine is cold. What causes that?

Cold-only misfires usually point to a coil breaking down when secondary resistance is highest, a cracked plug insulator arcing to ground, or an injector that's slow to open cold. Warm-only misfires more often mean a heat-sensitive coil or a compression issue that seals up as the head expands.

I replaced the plug and coil but P0305 came back. What next?

Move to the fuel and vacuum side. Check injector resistance (typically 12-16 ohms on port injection), listen with a mechanic's stethoscope for the click, and smoke-test the intake. If all that's clean, run a compression and leakdown test before spending more on parts.

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