Ignition Coil G Primary/Secondary Circuit
What it means
The engine computer has detected an electrical fault in the circuit of ignition coil G. This code usually appears on eight-cylinder engines, where coil G often serves cylinder 7, though the mapping varies by manufacturer, and it causes a misfire that may feel mild because of the many cylinders.
Symptoms4
- Check engine light on, possibly flashing during misfires.
- Mild to moderate shudder at idle.
- A misfire code for the cylinder served by coil G, often P0307.
- Higher fuel consumption and a fuel smell from the exhaust.
Possible causes6
- Failed ignition coil G.
- Loose or corroded coil G connector.
- Open or shorted control wire, especially near the exhaust manifold.
- Fault in the shared supply or ground for that bank's coils.
- Worn spark plug or damaged coil boot.
- Failed driver circuit inside the engine computer (rare).
How to diagnose5
- Identify the cylinder coil G serves from the service manual, because V8 cylinder numbering varies between manufacturers.
- Inspect the connector and wiring near the exhaust manifold for burned insulation.
- Swap coil G with another coil on the same bank, clear the codes and see whether the fault follows it.
- Measure supply and ground and check the control signal at the connector.
- Inspect that cylinder's plug for wear or cracks.
How to fix5
- Clean the connector and repair loose terminals.
- Repair burned or broken wiring and route it away from heat.
- Replace ignition coil G if the fault follows it.
- Replace the damaged plug in the same cylinder.
- Clear the codes, road test and confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low for a connector or wire repair, rises with a new coil and plug, and labor may increase depending on how easy the coil is to reach on the V8.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Why don't I feel strong shaking despite the code?
On an eight-cylinder engine one weak cylinder is less noticeable, but unburned fuel still harms the catalytic converter, so do not ignore the code.
Should I replace the plug along with coil G?
Not always, but inspect it when the coil is off. If it is worn, replace it, because it strains the new coil and can make it fail early.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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