P0674: Cylinder 4 Glow Plug Circuit

P0674 is a diesel-only code meaning the engine control unit detected an electrical fault in the glow plug circuit for cylinder 4. Glow plugs preheat each combustion chamber so a cold diesel can ignite. The code identifies the cylinder 4 circuit specifically, usually pointing to a failed plug, its wiring, or its connection rather than the whole system. Repairs typically run 30-180 EUR for a single plug and circuit fix.

P0674 è un codice diagnostico di guasto relativo a impianto elettrico, classificato con gravità moderate. Quando la centralina (ECU) del tuo veicolo rileva questa condizione, memorizza P0674 e accende la spia motore.

Se il tuo veicolo ha attivato P0674, potresti notare uno o più di questi sintomi:

• Check engine light or glow plug indicator illuminated
• Harder cold starts, especially in cold weather
• Brief cold misfire or stumble from cylinder 4 after startup
• White or grey smoke from the exhaust on cold start
• Longer cranking time before the engine catches
• Will likely fail a diesel technical or emissions inspection

Ecco le cause più comuni di P0674, ordinate in base alla probabilità che siano la causa del problema:

In genere sì, per brevi tragitti. Safe to drive once the engine is warm. This code flags the glow plug circuit for cylinder 4 only, and a single failed plug rarely stops a diesel from running. Expect harder cold starts, longer cranking, and a brief cold misfire from cylinder 4 with more white startup smoke. The car will likely fail a diesel inspection with this code stored.

Segui questi passaggi per individuare la causa principale di P0674:

1. Read the stored code and freeze frame with Skanyx or any ELM327 adapter to confirm P0674 and note the start temperature when it set
2. Locate the cylinder 4 glow plug and inspect its connector and wiring for corrosion, looseness, or damage
3. Disconnect the cylinder 4 glow plug and bench-test it with a multimeter: a healthy plug reads roughly 0.5-2 ohm, while an open (infinite) reading confirms that plug has failed
4. If the cylinder 4 plug is good, check continuity of its wiring back to the control module and verify a clean ground
5. Remember that per-cylinder glow plug live status is manufacturer-extended (Mode $22) data, not generic OBD2, so the multimeter test on the cylinder 4 plug is how you confirm the failure
6. Consider replacing the full set if the plugs are original and high-mileage, since the others are likely to fail soon

I costi di riparazione di P0674 variano a seconda della causa principale e del tuo veicolo. Ecco le stime tipiche:

P0674 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:

Questi codici compaiono spesso insieme a P0674 o indicano problemi correlati: