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.
DTC/P0674·Audi
P0674 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Audi
P0674 on a Audi 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.
Repair cost on Audi€6 - €483
What does P0674 mean on a Audi?
Audi A4 TDI
2004-2019The A4 TDI uses the same VAG per-plug monitoring as the Golf, so P0674 isolates cylinder 4. Some 2.0 and 3.0 TDI engines use fragile ceramic glow plugs that can snap if removed cold, so warm removal is essential. Replacing one plug is inexpensive unless a ceramic plug breaks off in the head.
What causes P0674 on a Audi?
Beyond the generic causes listed on the main P0674 page, these are the Audi-specific patterns we see most often:
Audi A4 TDIFailed cylinder 4 plug on VAG TDI engines
Audi A4 TDIFragile ceramic plug snapping on some 2.0/3.0 TDI
How to diagnose P0674 on a Audi with OBD2
Follow these steps to pinpoint the root cause of 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 on a Audi? (EUR)
Estimated repair costs on a Audi (Audi parts and labour typically run 15% above the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0674 on Audi
These codes commonly cluster with P0674 on Audi vehicles:
FAQ: P0674 on Audi
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. The car will likely fail inspection until it is fixed.
Do I need to replace all four 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 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.
Looking for the full P0674 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0674 guideSkanyx · Audi
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