What it means
Ignition L Control Signal Circuit/Open: the circuit is open. 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. P03FD sets when the module detects an open circuit, so the command cannot reach that coil group and the cylinders it serves may misfire.
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
- 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 scan-tool misfire counts to identify the conditions and cylinders associated with the open L circuit.
- With the ignition off, inspect the L control wire from the module toward the coil group for breaks, damage, or a disconnected plug.
- Check the connectors for a pushed-back or loose terminal and confirm each pin is seated and making contact.
- Test continuity through the L wire and its connections using the manufacturer's procedure to locate an open.
- If the harness and terminals pass, test the coil group and module output for an internal open or failed driver.
Common fixes
- Reseat a connector terminal that has backed out of its housing.
- Repair a broken or open L control wire.
- Clean or replace damaged connector terminals to restore contact.
- Repair a confirmed cracked module solder joint or replace the failed module after testing.
Can I keep driving?
A misfire can make the vehicle hesitate or lose power, so avoid heavy loads and drive only as needed to reach a safe place for repair. Stop if it will not start reliably or runs severely rough, since continued misfiring can damage 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.