What it means
The primary control circuit of ignition coil K 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 K 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
Ignition coil K is the coil identified by the vehicle’s control system for one cylinder; its primary circuit carries the low-voltage current used to build the coil’s magnetic field. The engine computer monitors the circuit for its expected electrical response. It sets P2331 when coil K’s primary control voltage remains higher than expected, commonly because of an open circuit or a control wire shorted to battery voltage.
Common causes
Most likely first.
- Open circuit in primary winding or harness for coil K
- 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 to see when the cylinder served by coil K starts misfiring.
- With the ignition off, inspect coil K’s connector and harness for a disconnected plug, corrosion, broken wire, or insulation pinched against a power source.
- Check coil K’s primary winding and connector terminals for an open or excessive resistance against the manufacturer’s specification.
- With the circuit isolated as directed by service information, check the primary control wire for continuity and for an unintended connection to battery voltage.
- If the coil and wiring pass, verify the control signal and engine computer driver using the manufacturer’s circuit test procedure.
Common fixes
- Reconnect coil K’s loose connector and clean or repair corroded terminals.
- Repair an open, damaged, or power-shorted coil K control wire.
- Replace coil K if its primary winding is open.
- Repair or replace the engine computer driver only after testing confirms the coil and harness are sound.
Can I keep driving?
Avoid hard acceleration and stop driving if the engine runs very rough or the check-engine light flashes; an active misfire can overheat and damage the catalytic converter. Arrange prompt diagnosis if the misfire continues.
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.