P0356

What it means

P0356 means the engine control unit has detected an open circuit in the primary control circuit of ignition coil F, normally the coil for cylinder 6 on a multi-cylinder engine. The control unit monitors the coil driver or trigger signal and sets the code when it sees no expected current or voltage response, which points to a break or high resistance in the circuit.

Symptoms

• Engine misfire, often on one cylinder, felt as shaking or hesitation
• Rough idle
• Loss of power and poor acceleration
• Malfunction indicator lamp on, possibly flashing under load
• Hard starting or stalling
• Increased fuel consumption

Possible causes

• Faulty ignition coil F with an open primary windinglikely
• Damaged, corroded or loose coil connector terminalslikely
• Open circuit or chafed wiring between the coil and the control unit in the trigger or control wirelikely
• Missing or poor power supply or earth to the coilpossible
• Blown fuse or faulty relay feeding the ignition coils (depends on model)possible
• Internal fault in the engine control unit driver for that coilrare

How to diagnose

1. Read all stored codes and freeze frame data to note engine load, speed and temperature when the fault set, and check for other misfire codes
2. Confirm which cylinder coil F relates to using the manufacturer's firing order and coil layout, as lettering varies by engine
3. Inspect the coil connector and wiring for damage, corrosion, heat damage, oil contamination and a secure fit
4. Swap coil F with a coil from another cylinder, clear the codes, and see whether the fault follows the coil
5. Check the coil power supply, earth and fuse with a multimeter against the wiring diagram
6. Test the control wire for continuity between the coil connector and the control unit connector, and check for shorts to earth or voltage
7. Check the trigger signal at the coil with an oscilloscope or suitable tester while cranking
8. Inspect the spark plug for that cylinder, since a worn plug can stress the coil and add to misfire

How to fix

• Replace the faulty ignition coil, and fit new spark plugs if they are worn or fouled
• Repair or replace damaged wiring or the connector, ensuring terminals are clean and tight
• Restore the power supply or earth, and replace any failed fuse or relay once the cause of failure is found
• Replace the engine control unit only after all wiring and component faults are ruled out, and have it coded as the manufacturer requires
• Clear the code and road test to confirm that it does not return

Can I keep driving?

Nearby codes

• P0355GenericIgnition Coil E Primary Control Circuit/Open
• P0357GenericIgnition Coil G Primary Control Circuit/Open