Fault code P0356 – a step-by-step guide to diagnosing and fixing it

Error code P0356 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected a fault in the ignition circuit of cylinder 6. This DTC P0356 indicates a problem with the ignition coil or the associated circuit of the sixth cylinder. Some manufacturers may also refer to this trouble code as "Ignition Coil F Primary/Secondary Circuit".

What causes can this fault code have?

• Defective ignition coil on cylinder 6
• Damaged ignition cables or plug connections
• Faulty spark plug in cylinder 6
• Short circuit or interruption in the ignition coil circuit
• Defective engine control unit (ECU)
• Corroded or loose plug connections
• Damaged wiring between ECU and ignition coil
• Insufficient voltage supply to the ignition coil

What symptoms occur in parallel with fault code P0356?

• Engine running unevenly: The engine runs unevenly and jerks when idling
• Power loss: Noticeable reduction in engine power, especially under load
• Misfiring: Engine stutters or stalls, especially when accelerating
• Increased fuel consumption: Engine works less efficiently
• Starting problems: Difficulty starting the engine
• Exhaust odor: Unburned fuel can be detected in the exhaust gas
• Check engine light: Permanently illuminated check engine light

How can I fix the problem with fault code P0356?

• Repairing fault code P0356 requires a systematic diagnosis to identify the exact cause.
• Replace the ignition coil of cylinder 6 and also replace the spark plug, as both components often wear out at the same time
• Check all plug connections to the ignition coil, clean and replace if corroded or damaged
• Measure the wiring between the engine control unit and ignition coil for continuity and insulation faults and replace defective cables
• Check the voltage supply to the ignition coil with a multimeter and rectify the cause in the power supply if the voltage is insufficient
• Replace the ignition coil with a functioning coil from another cylinder to check whether the fault is also present
• If the fault occurs repeatedly despite repair, have the engine control unit checked by a specialist workshop and replaced if necessary