Cylinder 10 Glow Plug Circuit
The glow plug for cylinder 10 isn't heating up properly, which makes cold diesel engine starts difficult. Think of it like a lighter that won't ignite—the engine needs that heat to start when it's cold.
The ECM monitors voltage and current draw from the cylinder 10 glow plug relay circuit during the glow plug pre-heat cycle. It detects open circuits, shorts, or excessive resistance that prevent proper heating. The circuit is typically energized for 5-10 seconds before cranking.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Glow plug circuit voltage | 11-14V supply during preheat | Below 10V or open circuit detected |
| Circuit current draw | 5-15A per glow plug | Zero amps or excessive current (short) |
Code P0680 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0680 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.