Code P0357 indicates that the engine computer has detected an open circuit in the primary control side of the ignition coil designated as 'G' (typically cylinder 7). This means the circuit that commands the coil to fire is electrically broken or disconnected, preventing the coil from operating and causing a misfire on that cylinder.
The internal primary winding of the ignition coil has failed open, breaking the electrical circuit inside the component itself.
The signal wire between the engine computer and the coil is broken, chafed, or disconnected, interrupting the circuit.
Corroded, pushed-back, or loose terminals in the ignition coil connector prevent the electrical signal from completing its path.
A blown fuse in the ignition coil power feed circuit can cause an open condition, though this often affects multiple coils simultaneously.
The internal driver circuit inside the engine computer has failed open and can no longer ground the coil, which is a rare occurrence.
The designation 'G' typically refers to cylinder 7, but the exact mapping varies by vehicle make, model, and engine layout. Always consult the specific service manual for the vehicle to identify which cylinder is assigned to coil G.
It is not recommended. Driving with a misfiring cylinder can dump unburned fuel into the exhaust, which can rapidly overheat and permanently damage the catalytic converter.
Rarely. While a failed PCM driver can cause this code, the vast majority of the time the cause is a failed ignition coil or a wiring/connector issue. The PCM should only be suspected after the coil, connector, and wiring have been thoroughly tested and confirmed to be good.
No. A bad spark plug will cause a misfire but will not set an open circuit code for the primary control circuit. However, a severely worn spark plug can overwork the ignition coil and contribute to its premature failure.