Genuine OEM NGK spark plug, same part used to service your BMW (1 step colder for N54, stock replacement for N55) FREE SHIPPINGSpark plugs are an often overlooked maintenance item. If your BMW has developed a misfire, studders, or feels down on power it could be due to worn out spark plugs. Please note Tightening torque for this spark plug is 23 ± 3 Nm, a special 14mm, 12 point spark plug socket is required for removal and installation of this plug. Spark Plug Failure Symptoms: Misfiring Check Engine Light Hesitation Loss of Power Poor Fuel Economy 1-Step Colder Spark Plugs for BMW N54 Engines Iridium electrodes for high performance 1-step colder heat range for knock resistance and misfire prevention Iridium tip electrodes which are tougher than the stock plugs Nickel-Copper tips