What it means
The primary control circuit of ignition coil F reads a voltage above the expected level — typically an open primary circuit or a short to battery voltage on the primary control wire. The ECU sees no normal current flow, coil F does not fire, and the cylinder misfires. Causes: an open or disconnected primary wire, an internal open in the coil, or a faulty ECU driver.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Coil F's primary control circuit carries the low-voltage current needed to charge the coil before it fires. This code means the control module detects voltage higher than expected, commonly because the circuit is open or shorted to a power supply; coil F may then fail to fire its cylinder.
Common causes
Most likely first.
- Open circuit in primary winding or harness for coil F
- Control line shorted to battery or supply
- Connector pins corroded - high contact resistance
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 whether the coil F cylinder is affected.
- With the ignition off, inspect coil F's connector and harness for a disconnected plug, broken wire, corrosion, or damage near a power source.
- Check that coil F's connector is fully seated and its terminals are clean and secure.
- Use the wiring diagram to test the coil F primary control wire for an open circuit or short to supply, comparing results with the manufacturer's specification.
- If the wiring is intact, test coil F's primary winding and control driver using the manufacturer's procedure.
Common fixes
- Reconnect and secure a loose coil F connector.
- Repair an open or damaged coil F primary wire.
- Repair a control wire shorted to battery or another supply.
- Replace coil F if its primary winding is open.
- Repair the control driver only if testing confirms it is faulty.
Can I keep driving?
Keep trips short and avoid hard acceleration while the coil F cylinder may be misfiring. If the check-engine light flashes or the engine runs roughly, stop when safe because unburned fuel can overheat 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.