What it means
Ignition K Control Signal Circuit High: the signal voltage is above the expected range. This line drives an ignition coil group; a fault causes misfire on those cylinders.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The ignition K control circuit carries the module’s command for a group of ignition coils. The module monitors the circuit’s electrical level and sets P03FC when it detects a voltage higher than expected, which can disrupt spark and cause misfires in the cylinders served by that group.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light on
- Engine misfire or rough running
- Hesitation or reduced power
- Possible hard starting or no-start
How to diagnose it
- Use a scan tool to save freeze-frame data and check misfire counts to see when the fault occurs and which cylinders are affected.
- With the ignition off, inspect the ignition K control wire and connectors for damage, corrosion, loose pins, or contact with a battery-positive feed.
- Check whether the K circuit voltage is above the expected range under the conditions described by the freeze frame.
- With power isolated as specified by the manufacturer, test the K wire for a short to battery positive and inspect any pinched sections closely.
- If the wiring and connections pass, test the coil group and module driver using the manufacturer's procedure before replacing parts.
Common fixes
- Repair a K control wire pinched against a power feed.
- Clean or repair corroded, loose, or damaged connector terminals.
- Repair a short to battery positive in the K circuit.
- Replace a failed coil-group component or module driver only after circuit tests confirm the fault.
Can I keep driving?
If the engine is misfiring or losing power, avoid hard acceleration and long trips; unburned fuel can overheat and damage the catalytic converter. Stop driving if it runs very roughly or is difficult to keep running.
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.