Can I drive with a P0674 code?

Yes. This flags only the cylinder 4 glow plug circuit, and one dead plug rarely stops a diesel from running. You will get harder cold starts and a brief cold misfire from that cylinder.

Do I need to replace all the glow plugs for P0674?

Not strictly. P0674 points to cylinder 4, so you can replace just that plug. But if the plugs are original and high-mileage, replacing the full set (four on a four-cylinder diesel, six on a V6 such as the 3.0 TDI) while you are in there avoids repeat labor when the next plug fails.

How do I confirm the cylinder 4 glow plug is the problem?

Disconnect the cylinder 4 plug and measure its resistance with a multimeter. A good plug reads about 0.5-2 ohm. An open reading confirms it has failed. Generic OBD2 only tells you the circuit, not the plug condition.

Why does only one cylinder set a glow plug code?

Each glow plug has its own circuit the control module monitors. When the cylinder 4 plug or its wiring goes open or shorted, the module reports that specific circuit, which is why you see a per-cylinder code rather than a general one.

P0674: Cylinder 4 Glow Plug Circuit

Quick Answer

Safe to drive (short-term)

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.

Severity: Moderate · Electrical
Estimated repair cost: From €5 to €420+, varies by vehicle

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What does P0674 mean?

P0674 is a electrical-related diagnostic trouble code classified as moderate severity.

What are the symptoms of P0674?

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
Higher exhaust emissions until the engine warms up

What causes P0674?

Failed cylinder 4 glow plug (open circuit)
: high
Corroded or loose connector at the cylinder 4 glow plug
: medium
Open or shorted wiring to the cylinder 4 plug
: medium
Faulty glow plug control module output for cylinder 4
: low
Poor ground at the cylinder 4 glow plug
: low

Is it safe to drive with P0674?

Generally yes, for short-term driving. 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. A stored emissions-related fault is the kind of defect that gets a car rejected at inspection, so have it fixed before you book one.

How do you diagnose P0674?

Read the stored code and freeze frame with Skanyx or any ELM327 adapter to confirm P0674 and note the start temperature when it set
Locate the cylinder 4 glow plug and inspect its connector and wiring for corrosion, looseness, or damage
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
If the cylinder 4 plug is good, check continuity of its wiring back to the control module and verify a clean ground
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
Consider replacing the full set if the plugs are original and high-mileage, since the others are likely to fail soon

How much does P0674 cost to fix?

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Replace cylinder 4 glow plug (DIY)	€10–€30	€0–€0	€10–€30	Moderate
Repair cylinder 4 connector/wiring (DIY)	€5–€25	€0–€0	€5–€25	Moderate
Replace cylinder 4 glow plug (shop)	€10–€30	€40–€120	€50–€150	Moderate
Replace full glow plug set as preventive (shop)	€60–€200	€90–€220	€150–€420	Professional

Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.

P0674 on specific vehicles

P0674 on Volkswagen

Volkswagen Golf TDI

See Volkswagen-specific causes & cost

P0674 on BMW

BMW 320d

See BMW-specific causes & cost

P0674 on Audi

Audi A4 TDI

See Audi-specific causes & cost

P0674 on Mercedes-Benz

Mercedes-Benz (OM651 diesel)

See Mercedes-Benz-specific causes & cost

Common questions about P0674

Can I drive with a P0674 code?: Yes. This flags only the cylinder 4 glow plug circuit, and one dead plug rarely stops a diesel from running. You will get harder cold starts and a brief cold misfire from that cylinder.
Do I need to replace all the glow plugs for P0674?: Not strictly. P0674 points to cylinder 4, so you can replace just that plug. But if the plugs are original and high-mileage, replacing the full set (four on a four-cylinder diesel, six on a V6 such as the 3.0 TDI) while you are in there avoids repeat labor when the next plug fails.
How do I confirm the cylinder 4 glow plug is the problem?: Disconnect the cylinder 4 plug and measure its resistance with a multimeter. A good plug reads about 0.5-2 ohm. An open reading confirms it has failed. Generic OBD2 only tells you the circuit, not the plug condition.
Why does only one cylinder set a glow plug code?: Each glow plug has its own circuit the control module monitors. When the cylinder 4 plug or its wiring goes open or shorted, the module reports that specific circuit, which is why you see a per-cylinder code rather than a general one.

Read our detailed guides

Scan your car with Skanyx to diagnose P0674