P0357
Ignition Coil G Primary Control Circuit/Open.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 3
- AreaIgnition system or misfire
- 57
- FaultThe specific fault in that area
What it means
P0357 means the engine control module has detected an open circuit in the primary control circuit of ignition coil G, which is the seventh coil in the manufacturer's numbering. The module monitors the coil driver or the ignition feed and sets the code when the expected electrical response is missing. Which cylinder coil G serves depends on the engine and manufacturer.
Symptoms
- Engine misfire, often on one cylinder, causing rough running
- Malfunction indicator lamp on, possibly flashing under load
- Hesitation or loss of power when accelerating
- Rough idle or difficult starting
- Poor fuel economy
- Possible stored misfire codes for the related cylinder
Possible causes
- Faulty ignition coil with an open primary windinglikely
- Damaged, chafed or broken wiring in the coil control circuitlikely
- Corroded, loose or pushed-out pins in the coil connectorlikely
- Missing or intermittent power or earth supply to the coilpossible
- Blown fuse or faulty relay feeding the ignition coilspossible
- Fault in the engine control module driver circuitrare
How to diagnose
- Read all stored codes and freeze frame data to see engine load, speed and temperature when the fault set, and note any misfire codes
- Find out which cylinder coil G serves on this engine using the manufacturer's information, as the layout varies by model
- Inspect the coil connector and wiring for damage, heat, oil contamination, corrosion and poor pin tension
- Check the relevant fuse and relay, and confirm the coil has a good power supply and earth with the ignition on
- Swap coil G with a known good coil, clear the code and see whether the fault follows the coil
- Test the control wire between the coil and the control module for continuity, short circuits and resistance against the wiring diagram
- Check the control signal at the coil connector while cranking, following the manufacturer's procedure
- Inspect the spark plug for that cylinder, as a worn plug can stress the coil, but do not assume it caused an open circuit
How to fix
- Replace the faulty ignition coil and check the spark plug for that cylinder at the same time
- Repair or replace damaged wiring in the coil control circuit
- Clean, repair or replace the corroded or damaged connector terminals
- Restore the power or earth supply, including replacing a faulty fuse or relay after finding why it failed
- Replace or repair the engine control module only after the wiring and coil are confirmed good and the manufacturer's procedure supports it
Can I keep driving?
Medium severity
The car can usually be driven short distances, but the misfire can overheat the catalytic converter and worsen with time. Avoid heavy loads, and stop driving if the warning lamp flashes.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.