P0680 — Cylinder 10 Glow Plug Circuit/Open

The trouble code P0680 indicates an issue within the glow plug circuit for cylinder 10. This code signals that the engine’s control module (ECU) has detected a possible open circuit or malfunction in the glow plug associated with this specific cylinder. Note that labels and descriptions of this code can vary slightly between different vehicle manufacturers, but the core meaning remains consistent.

Manufacturer variations for trouble code P0680

Different vehicle manufacturers may label or code this problem slightly differently, sometimes depending on regional or proprietary diagnostic conventions. While the core issue remains the same—an open or faulty circuit for cylinder 10 glow plug—manufacturers may assign distinct codes or descriptions. Here are some known variations:

• Volkswagen / Audi: P0680 — Glow plug circuit 10 — open circuit
• BMW: 5E36 — Glow plug circuit showing open circuit (specific to BMW systems)
• Mercedes-Benz: A0014 — Glow plug circuit open in cylinder 10
• Peugeot / Citroën: P1339 — Glow plug circuit fault (may include specific cylinder notation)

What does trouble code P0680 mean?

In simple terms, P0680 points to a problem within the control circuit for cylinder 10 glow plug. The engine’s ECU continuously monitors the electrical circuit that powers the glow plug—used predominantly in diesel engines to assist in cold starting. When the ECU detects that it cannot complete the circuit—meaning there’s an open circuit, broken wire, or faulty component—it triggers this specific fault code.

This detection typically occurs during startup, especially in cold weather conditions, as the glow plugs are essential for efficient combustion at low temperatures. The code may also appear if there is an issue with the relay, wiring, or the glow plug itself. Essentially, when the circuit for cylinder 10’s glow plug isn’t complete or is interrupted, the ECU flags this fault.

Severity and risks of trouble code P0680

The severity of P0680 can range from moderate to high depending on driving conditions. The primary risk involves difficult cold starts, which can lead to increased emissions, poor engine performance, and potential damage if the problem is left unaddressed. However, this fault does not necessarily affect the vehicle’s ability to run once the engine has warmed up, unless related issues persist.

In terms of risks, ignoring this code could lead to prolonged issues starting the vehicle in cold weather, potentially causing unnecessary wear on the glow plug relay or wiring. Instant driveability may be limited, especially during winter conditions, but in many cases, the vehicle can still be driven if the problem is not severe. Overall, Limited — the vehicle can often be driven but with caution and awareness of starting difficulties.

Symptoms of trouble code P0680

Typically, drivers may notice several symptoms when encountering P0680. These are often subtle at first but can become more evident over time or during cold weather. The most common signs include:

• Difficulty starting the engine, especially in cold conditions
• Engine warning light (check engine light) illuminated
• Rough idle or hesitation during startup
• Increased emissions or a failed emissions test
• Possible malfunction indicators related to glow plug system

Most likely causes of trouble code P0680

Understanding the causes of P0680 is instrumental in proper diagnosis and repair. This fault mainly originates from electrical or component-related issues within the glow plug circuit for cylinder 10. The causes are ranked from most to least common:

1. Open circuit or broken wiring in the glow plug control circuit: This is the most frequent cause, often due to wear, corrosion, or mechanical damage.
2. Faulty glow plug for cylinder 10: The glow plug itself may have failed internally, causing an open circuit.
3. Malfunctioning glow plug relay or control module: The relay that switches power to the glow plug might fail, preventing proper operation.
4. Corroded or loose electrical connectors: Poor connections can interrupt current flow, triggering the code.
5. Blown fuse or electrical overload in the circuit: Overcurrent might have caused a fuse to blow, cutting off power to the glow plug.

How to diagnose trouble code P0680

Diagnosing P0680 involves a systematic approach to isolate the cause. Here are generic steps that can be followed safely and effectively:

1. Visual inspection: Check wiring, connectors, and the relay box related to the glow plug circuit for signs of damage, corrosion, or loose connections.
2. Verify electrical connections: Ensure all plugs and terminals are securely connected and free from corrosion.
3. Test the glow plug wiring continuity: Use a multimeter to check for continuity between the glow plug connector and ECU control module. An open circuit indicates damage or breakage.
4. Inspect the glow plug: Remove and test the glow plug for internal resistance or short circuits as per manufacturer’s specifications.
5. Check the glow plug relay: Test the relay for proper operation, swapping it with a known-good relay if possible.
6. Scan live data: Use a compatible diagnostic scanner to observe real-time data of the glow plug circuit during activation.
7. Examine related fuses: Inspect the fuse linked to the glow plug circuit and replace if blown.

Possible repairs for trouble code P0680

Depending on the identified cause during diagnosis, repairs can range from simple to more complex actions. Here are potential fixes:

• Replace damaged wiring or connectors: Basic repair needed if wiring or connectors are corroded, broken, or frayed. A professional is recommended for proper re-soldering or sealing.
• Replace the glow plug: If testing reveals a faulty glow plug, replacement is necessary. This is often a straightforward repair but may require engine cooling and some disassembly.
• Replace or repair the glow plug relay: A faulty relay can be swapped out for a new one. Ensure proper matching to the vehicle specifications.
• Fix or replace blown fuse or electrical overload component: Replace the fuse and investigate potential causes of overcurrent.
• Address underlying electrical issues: For persistent issues, a professional diagnosis may involve wiring harness repairs or ECU reprogramming.

Vehicles commonly associated with trouble code P0680 in Europe

This fault is typically found in diesel-powered vehicles equipped with specific glow plug systems. In Europe, vehicles from the following brands are often affected:

Volkswagen Group (including Volkswagen, Audi, Škoda, SEAT): These vehicles often share components and design principles, making glow plug circuit faults common, especially on diesel engines.

BMW: Certain diesel engine models may report similar faults related to glow plug circuits.

Mercedes-Benz: Diesel models, especially those with advanced glow plug control units, may Experience this fault.

It’s crucial to consult individual vehicle repair manuals for specific engine families or models affected, as diagnostic protocols can vary.

Frequent mistakes with trouble code P0680

Diagnosing and repairing P0680 requires careful attention. Common mistakes include:

• Replacing parts without proper testing: Changing a glow plug or relay without confirming the fault can lead to unnecessary repairs.
• Ignoring wiring and connector issues: Overlooking corrosion or loose connections often causes the same fault repeatedly.
• Overlooking related system components: Focusing solely on the glow plug itself rather than the control circuit or relay can result in incomplete repairs.
• Failing to verify battery condition: A weak or failing battery can affect glow plug operation and trigger fault codes falsely.

Quick FAQ — trouble code P0680

Can this code disappear on its own?

Yes. Sometimes, transient electrical issues or poor connections can trigger the code temporarily. Once the faulty connection is corrected or the vehicle is restarted, the code may clear itself. However, persistent issues require proper diagnosis and repair.

Can I keep driving?

Limited — while the vehicle can often be driven with this fault, especially once warmed up, starting difficulties in cold weather can occur. Continuous driving without addressing the root cause can potentially lead to further engine or electrical problems.

Why does the code return after clearing?

The code reappears because the underlying cause—such as a damaged wiring, faulty glow plug, or relay—is still present and triggering the safety circuit detection. Until the fault is repaired, the ECU will continue to generate the fault code.