What it means
Ignition F control signal stuck low — short to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
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 the F control signal and sets this code when the circuit voltage is lower than expected, which can occur if the wire is shorted to ground.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on or flashing
- Engine misfire or rough running
- Power loss or hesitation
- Hard starting
How to diagnose it
- Record freeze-frame data and check live misfire counts to see whether the fault is active and which cylinder is affected according to the vehicle's coil mapping.
- Inspect the Ignition F coil connector and harness for rubbed-through insulation, moisture, corrosion, or loose and backed-out pins.
- Monitor the F control signal with a scan tool or suitable meter while gently moving the harness to look for an intermittent change.
- With the circuit isolated as specified by the manufacturer, check whether the F control wire is shorted to ground.
- If the harness passes, test the F coil and the module's F-channel driver according to the manufacturer's procedure.
Common fixes
- Repair the chafed Ignition F wire where it contacts ground.
- Clean and dry the F connector and repair corroded or loose terminals.
- Replace a coil that fails the manufacturer's Ignition F coil tests.
- Repair or replace the control module only if its F driver is confirmed faulty.
Can I keep driving?
If the engine is misfiring, avoid hard acceleration and stop driving if the check-engine light flashes; a sustained misfire can damage the catalytic converter. If the light is steady and the engine runs normally, keep any trip short and gentle while arranging 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.