Fault code P0354 – a step-by-step guide to diagnosing and fixing it

Error code P0354 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected a fault in the ignition coil circuit of cylinder 4. This DTC P0354 indicates problems with the ignition coil, the cables or the control unit of the fourth cylinder. The exact designation may vary for different manufacturers, but the fault code always refers to the ignition system of the fourth cylinder.

What causes can this fault code have?

• Defective ignition coil on cylinder 4
• Damaged ignition cable or spark plug connector
• Defective spark plug in cylinder 4
• Loose or corroded plug connections
• Short circuit or interruption in the wiring
• Defective engine control unit (ECU)
• Poor ground connection in the ignition circuit
• Overheating of the ignition components

What symptoms occur in parallel with fault code P0354?

• Engine running unevenly: The engine runs unevenly and jerks, especially when idling
• Loss of power: Noticeable reduction in engine power and acceleration
• Misfiring: Misfiring in cylinder 4, which can be perceived as jerking
• Increased fuel consumption: The engine operates inefficiently due to the defective cylinder
• Starting problems: Difficulties with cold starts or prolonged starting behavior
• Exhaust odor: Unburned fuel can lead to unusual exhaust emissions

How to fix the problem of error code P0354?

• The repair requires a systematic diagnosis to identify the exact cause.
• Replace the ignition coil of cylinder 4 with a new one and then test whether the trouble code disappears
• Check the spark plug of the fourth cylinder and replace if worn or damaged
• Clean all plug connections of the ignition system, check for tight fit and replace if corroded
• Check the ignition cable and spark plug connector for damage and replace defective parts
• Measure the wiring to the ignition circuit with a multimeter and repair if there is an interruption or short circuit
• Check the ground connections of the ignition system, clean and replace if necessary
• Have the engine control unit tested for defects and repair or replace if necessary