What it means
A fault is detected on the secondary (high-voltage) side of ignition coil F. The spark delivered to the plug is missing or too weak, causing a misfire on the cylinder served by coil F. Causes: a worn spark plug or wide gap, a cracked coil or boot, carbon tracking, or an open or leaking secondary winding.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Ignition coil F sends high voltage through its boot or lead to the spark plug for the cylinder it serves. The control module detects a fault on this secondary path when the spark is missing or too weak, which can cause that cylinder to misfire.
Common causes
Most likely first.
- Spark plug worn, fouled or with excessive electrode gap
- Secondary breakdown inside coil F
Symptoms
- Check-engine light on, possibly flashing
- Engine misfire or rough idle
- Hesitation under acceleration
- Reduced power
How to diagnose it
- Record freeze-frame data and check live misfire counts to confirm when the coil F cylinder misfires.
- Inspect the coil F boot and spark plug for cracks, carbon tracking, fouling, wear, or an excessive gap.
- Check that the plug and coil connections are secure and that the plug matches the manufacturer's specification.
- If the design allows, swap coil F with a matching coil on another cylinder and see whether the misfire follows it.
- If the fault stays with the cylinder, test coil F's secondary path and winding using the manufacturer's procedure.
Common fixes
- Replace a worn, fouled, or incorrectly gapped spark plug on the coil F cylinder.
- Replace a cracked or carbon-tracked coil F boot or lead.
- Replace coil F if its secondary winding fails testing.
- Repair a damaged connection in the coil F secondary path.
Can I keep driving?
Avoid hard acceleration and arrange prompt repair. If the check-engine light flashes or the engine shakes badly, stop driving when safe; continued misfire can damage the catalytic converter.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.