What it means
The ignition F control signal circuit is open — typically the PCM drive line for the first ignition coil group has lost continuity.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Ignition F is a designated ignition-coil control channel; the letter does not identify a universal cylinder. The control module monitors continuity in the F control circuit and sets this code when the circuit appears open, so the F coil may not receive its control signal and spark may be lost.
Common causes
Most likely first.
- Open wire between PCM and coil
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check engine light on or flashing
- Engine misfire or rough running
- Power loss or hesitation
- Hard starting
How to diagnose it
- Save freeze-frame data and check live misfire counts for a cylinder or operating condition associated with the F channel, using vehicle-specific coil mapping.
- Inspect the Ignition F coil connector and harness for a disconnected plug, damaged wire, backed-out pin, or corrosion.
- Check that the F coil has its required power and ground supplies, following the wiring diagram and manufacturer's specifications.
- With power off and the circuit isolated as specified, check continuity through the F control wire between the module and coil.
- If the wire and terminals are intact, test the F coil and module driver using the manufacturer's procedure.
Common fixes
- Reconnect the F coil plug or secure a loose connector.
- Repair an open or damaged section of the Ignition F control wire.
- Replace a pushed-back or corroded terminal and restore connector sealing.
- Replace the F coil or repair the module only if testing confirms that component has failed.
Can I keep driving?
Avoid hard acceleration if the engine is misfiring, and stop driving if the check-engine light flashes because an active misfire can overheat the catalytic converter. A steady light with smooth running may allow a short, gentle trip for diagnosis.
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.