What it means
The primary control circuit of ignition coil L reads a voltage above the expected level — typically an open primary circuit or a short to battery voltage on the primary control wire. The ECU sees no normal current flow, coil L does not fire, and the cylinder misfires. Causes: an open or disconnected primary wire, an internal open in the coil, or a faulty ECU driver.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The coil L primary control circuit carries the switched current that charges ignition coil L before it fires its cylinder's spark plug. This code means the controller sees voltage higher than expected on that control circuit, commonly because the circuit is open or shorted to battery voltage, so coil L may not fire.
Common causes
Most likely first.
- Open circuit in primary winding or harness for coil L
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light
- Engine misfire or rough running
- Reduced power or hesitation
How to diagnose it
- Save freeze-frame data and review misfire counts for the coil L cylinder to establish whether the fault coincides with a misfire.
- With the ignition off, inspect coil L's connector and harness for a disconnected plug, broken wire, pushed-back pin, or damage near a power source.
- Check coil L's power supply and connector seating against the vehicle wiring diagram and manufacturer's procedure.
- Test the coil L primary control wire for continuity and for a short to battery voltage, isolating the coil and controller as directed by the manufacturer.
- Test the coil L primary winding and ECU or igniter driver if the harness checks do not identify the open or high-voltage condition.
Common fixes
- Reconnect coil L's loose connector or repair an open control wire.
- Repair wiring shorted to battery voltage and secure it away from the power source.
- Clean or replace damaged coil L connector terminals.
- Replace coil L if its primary winding is open.
- Repair the ECU or igniter driver only if testing confirms it is faulty.
Can I keep driving?
Avoid hard acceleration and limit driving if the coil L cylinder is misfiring, since unburned fuel can damage the catalytic converter. Stop if the check-engine light flashes or the engine runs severely rough.
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.