Fault code P0351 – a step-by-step guide to diagnosing and fixing it

Error code P0351 is displayed and the check engine light is on - what does this mean?

The DTC P0351 is recognized by the OBD system when there is a problem in the primary circuit of the ignition coil of the first cylinder. This fault code indicates a fault in the ignition system, which the engine control unit reports via the EOBD system. This code may have slightly different names for different manufacturers, but always refers to cylinder 1.

What causes can this fault code have?

• Defective ignition coil cylinder 1
• Damaged or corroded ignition cable
• Loose or corroded plug connections to the ignition coil
• Defective spark plug in cylinder 1
• Short circuit in the ignition coil circuit
• Faulty wiring between engine control unit and ignition coil
• Defective engine control unit (rare)
• Poor ground connection of the ignition coil

What symptoms occur in parallel with fault code P0351?

• Engine running unevenly: The engine runs unevenly and vibrates strongly
• Misfiring: Noticeable misfiring, especially when idling
• Loss of power: Reduced engine power when accelerating
• Increased fuel consumption: The engine requires more fuel than usual
• Starting problems: Difficult starting or longer starting times
• Exhaust odor: Unburned fuel can be smelled in the exhaust gas
• Jerking when driving: Particularly noticeable at low engine speeds

How can the problem with error code P0351 be rectified?

• The repair requires a systematic diagnosis of the ignition system of the first cylinder.
• Replace ignition coil cylinder 1: Replace the defective ignition coil with a new original coil and clean the plug connections
• Replace spark plug: Replace worn or defective spark plug with a suitable new plug
• Check and repair wiring: Replace damaged cables to the ignition coil and check all connections for corrosion
• Clean plug connections: Clean all electrical connections to the ignition coil and treat with contact spray
• Check the ground connection: Localize poor ground connection of the ignition coil and make a new ground connection
• Maintain the entire ignition system: Replace all ignition components at the same time to prevent further failures