12120039664-NGK-KT6 These NGK Laser Iridium replacement plugs are factory standard in BMW N20 & S55 motors. They are 2 steps colder than stock N54 plugs and suggested for higher boost E85, water/meth injection, and/or upgraded turbocharger applications across all late model turbo BMW models. We suggest setting the gap down to 0.020".NGK's Laser Iridium Spark Plugs Provide Superior Ignitability and Long Service Life. Fine Wire Iridium Tipped Center Electrode and Fine Wire Platinum Tipped Ground Electrode Ensures Slow Wear Rate Providing Stable Idle, Superior Anti Fouling, Improved Fuel Efficiency, and Lower Emissions. Spark 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, the gap is preset for OE applications only, a special 14mm, 12 point spark plug socket is required for the removal and installation of this plug, please see p/n 83300495560 for the correct tool. NGK and offers 2-step colder spark plugs for the BMW N55 engine. These colder spark plugs are recommended for N55's who are running higher than stock boost. The 1-step colder plugs will likely need to be changed every 15,000 miles, on heavily modified cars, or sooner if the engine is experiencing rough idling, longer starts, or misfiring. The stock heat ranges on the N55 are one-step lower than the N54, therefore these plugs are one-step colder for the N55, and two steps colder for the N54. Why Opt for 1-Step Colder Plugs? It should be noted - running colder spark plugs will not necessarily increase power (although it may restore power if the current plugs are old). These spark plugs are not recommended for stock boost as the spark plug will not retain enough heat to burn carbon deposits, thereby significantly reducing the life and effectiveness of the plugs. If your BMW N55 is modified, tuned, FBO, etc., the 1-step colder spark plugs are the best option. These spark plugs are more efficient at transferring heat and reducing the likelihood of engine knocks or pre-detonation, which becomes a concern at higher boost and horsepower levels. NOTE: These spark plugs need to be individually gapped to 0.020" (0.508mm) using a spark plug gapping tool. Additionally, these are the OEM plugs for the N20 and N26 turbocharged four-cylinder engines. Specifications:Center electrode core material: CopperCenter electrode tip material: IridiumElectrical terminal type: Non-removable nutGround Configuration: StandardGround electrode core material: CopperGround electrode quantity: 1Ground electrode tip design: SPE (Square platinum electrode)Hex size: 14mm bi-hex (12 point) - see p/n 83300495560 for the correct socketThread size: 12x1.25mmTorque spec: 23 ± 3 Nm (~17 ft-lb)Insulator Height: 50mmManufacturer heat range: 8Pre-gap size: .03" (.762mm) - Pregapped for OE applicationsReach: 26.5mmResistance: 5000 ohmsResistor Type: YesSeat Type: Flat Spark Plug Maintaining your car at suggested service intervals will result in better performance and improved fuel economy, which is why we suggest changing your spark plugs at the manufacturer's suggested service intervals and be sure to check their condition for any warning signs of failure. If your vehicle isn't operating at peak performance it may be time to replace your spark plugs. Spark Plug Failure Symptoms Misfiring Check Engine Light Hesitation Loss of Power Poor Fuel Economy This Part Fits The Following Vehicles MAKE MODEL SUBMODEL ENGINE DRIVETRAIN BMW 1 Series E8X (2008-2013) 135i N55 3.0L BMW 2 Series F2X (2014+) M235i N55 3.0L BMW 2 Series F2X (2014+) M235i xDrive N55 3.0L BMW 2 Series F87 (2016+) M2 N55 3.0L BMW 3 Series F3X (2012-2019) 335i N55 3.0L BMW 3 Series F3X (2012-2019) 335i xDrive N55 3.0L BMW 3 Series F80 (2015-2019) M3 S55 3.0L BMW 4 Series F3X (2014-2019) 435i N55 3.0L BMW 4 Series F3X (2014-2019) 435i xDrive N55 3.0L BMW 4 Series F8X (2015-2020) M4 M4 S55 3.0L BMW 5 Series F10 (2011-2016) 535i N55 3.0L BMW 5 Series F10 (2011-2016) 535i xDrive N55 3.0L BMW 6 Series F1X (2012-2018) 640i N55 3.0L BMW 6 Series F1X (2012-2018) 640i xDrive N55 3.0L BMW 7 Series F01/F02 (2009-2015) 740i N55 3.0L BMW 7 Series F01/F02 (2009-2015) 740Li N55 3.0L BMW 7 Series F01/F02 (2009-2015) 740Li xDrive N55 3.0L BMW X Series X1 E84 (2012-2015) xDrive35i N55 3.0L BMW X Series X3 F25 (2011-2017) xDrive 2.8i N52 3.0L BMW X Series X3 F25 (2011-2017) xDrive 3.5i N55 3.0L BMW X Series X4 F26 (2015-2017) xDrive35i N55 3.0L BMW X Series X5 E70 (2007-2013) xDrive35i N55 3.0L BMW X Series X5 F15 (2014-2018) sDrive35i N55 3.0L BMW X Series X5 F15 (2014-2018) xDrive 35i N55 3.0L BMW X Series X6 E71 (2008-2014) xDrive35i N55 3.0L (2011+) BMW Z Series E89 (2009-2016) Z4 28i BMW Z Series E89 (2009-2016) Z4 30i BMW Z Series E89 (2009-2016) Z4 35i BMW Z Series E89 (2009-2016) Z4 35is