What it means
An electrical fault is detected in both the primary and the secondary circuit of ignition coil G. The ECU cannot drive the coil correctly, so the cylinder served by coil G misfires or does not fire at all. Causes: an open or shorted primary control wire, an internal coil winding fault, a failed igniter/driver, or wiring or connector damage at the coil.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Coil G's primary winding is switched by the ignition control system to create the spark for its assigned cylinder. The control module monitors the coil G primary and secondary circuit response and sets P0357 when it detects an electrical fault that may leave that cylinder misfiring or unfired.
Common causes
Most likely first.
- Ignition coil G failure
- Open, shorted, or damaged coil wiring
- Loose or corroded connector
- Fault in the ignition control driver
Symptoms
- Check engine light on or flashing
- Engine misfire or rough running
- Power loss or hesitation
- Hard starting
How to diagnose it
- Capture freeze-frame data and check misfire counts with a scan tool to see whether the fault is tied to a specific cylinder or operating condition.
- Inspect coil G and its connector for corrosion, loose or pushed-back pins, damaged insulation, or overheating.
- Check the coil G power and control wiring for opens or shorts using the vehicle wiring diagram and manufacturer's specification.
- Test coil G's windings and secondary path according to the manufacturer's procedure.
- If the coil and harness pass, test the ignition control driver and its module connections for coil G.
Common fixes
- Reconnect or secure the coil G connector.
- Repair damaged wiring or connector terminals in the coil G circuit.
- Replace coil G if testing finds an internal winding or secondary-path fault.
- Repair the coil G driver circuit or replace the module if its driver is confirmed faulty.
Can I keep driving?
Avoid driving if the engine is running roughly or the check-engine light flashes, because continued misfire can damage the catalytic converter. If the engine runs smoothly and the light is steady, limit driving and get the fault checked promptly.
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.