Ignition Coil "G" Primary Control Circuit Low
P2318 indicates the ignition coil G primary control circuit is detecting a low voltage condition. The PCM is unable to properly command the ignition coil, which can prevent spark generation for that cylinder and cause misfires.
What You Might Notice
- Engine misfire or rough idle
- Diminished engine performance and power loss
- Reduced fuel efficiency
- Check Engine light illuminated
- Difficulty starting the engine
Most Common Causes
- 1
Faulty ignition coil G
The ignition coil itself may be failing or have internal resistance issues, preventing proper voltage delivery to the spark plug.
- 2
Wiring or connector issues
Corroded, loose, or damaged wiring/connectors in the ignition coil circuit can cause low voltage signals and poor electrical connection.
- 3
PCM control circuit malfunction
The powertrain control module may have a faulty driver circuit that controls the ignition coil, preventing proper voltage delivery.
- 4
Engine ground or power supply issues
Poor ground connections or low battery voltage can result in insufficient power reaching the ignition coil control circuit.
How to Diagnose It
- 1
Check Faulty ignition coil G — The ignition coil itself may be failing or have internal resistance issues, preventing proper voltage delivery to the spark plug.
- 2
Check Wiring or connector issues — Corroded, loose, or damaged wiring/connectors in the ignition coil circuit can cause low voltage signals and poor electrical connection.
- 3
Check PCM control circuit malfunction — The powertrain control module may have a faulty driver circuit that controls the ignition coil, preventing proper voltage delivery.
- 4
Check Engine ground or power supply issues — Poor ground connections or low battery voltage can result in insufficient power reaching the ignition coil control circuit.
How to Fix It
- 1
Replace ignition coil G
Remove and replace the ignition coil for cylinder G with a new OEM or quality aftermarket coil pack, then clear the code and test drive.
- 2
Inspect and repair wiring/connectors
Check all wiring and connectors in the ignition coil circuit for corrosion, damage, or looseness. Clean contacts and repair or replace damaged harnesses as needed.
- 3
Test and verify power supply
Verify battery voltage and ground connections are solid, and confirm proper voltage is reaching the ignition coil control circuit using a multimeter.
- 4
Diagnose PCM control circuit
If coil and wiring are sound, use a scope or specialized diagnostic equipment to test the PCM's ignition coil driver circuit; PCM replacement may be necessary if faulty.
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