What it means
Ignition L Control Signal Circuit Low: the signal voltage is below 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 L control circuit carries the module’s command for a group of ignition coils. The module sets P03FE when the L circuit voltage falls below its expected range, which can interrupt coil control and cause misfires in the cylinders served by that group.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Engine misfire or rough running
- Hesitation or reduced power
- Possible hard starting or no-start
How to diagnose it
- Save freeze-frame data and check misfire counts to see when the low signal occurs and which cylinders are affected.
- With the ignition off, inspect the L control wire and connectors for chafed insulation, a loose plug, or corrosion.
- Check the L circuit signal against the manufacturer's expected range while observing the conditions that set the code.
- With power isolated as specified by the manufacturer, test the L wire for a short to ground, paying attention to rubbed or pinched sections.
- If the wiring and terminals pass, test the coil group and module driver before replacing either component.
Common fixes
- Repair chafed insulation where the L wire is contacting ground.
- Clean, tighten, or replace corroded L circuit connector terminals.
- Repair a confirmed short to ground in the harness.
- Replace a failed coil-group component or module driver only after testing confirms the fault.
Can I keep driving?
If the engine misfires or hesitates, avoid hard acceleration and unnecessary driving because continued misfiring can overheat the catalytic converter. Stop if the engine runs severely rough or loses enough power to make driving unsafe.
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.