BMW Spark Plug Wire Set - Genuine BMW 12121726037

Product Information

BMW Spark Plugs diagram for 525i

A spark plug wire set is a main component in the ignition system of older gasoline vehicles that use a distributor. The primary function of spark plug wires is to transmit the high-voltage electricity generated by the ignition coil to the spark plugs. The wires are designed to handle very high voltage without too much resistance or causing electrical interference to other systems. A good quality set of spark plug wires ensures efficient combustion, optimal engine performance, and smooth vehicle operation.

Four main components make up a spark plug wire set: The conductive cable itself, which is often a spiral wound wire around a core material to help abate interference and improve durability, the insulation layer, the spark plug boots, and the connectors. Depending on the application, some spark plug wire sets may or may not include the ignition coil wire that goes between the ignition coil and distributor, so be sure to check before ordering.

When a spark plug wire set is worn out or in need of replacement, the engine will struggle to run at peak efficiency, misfire, and in some conditions may not allow the engine to run at all. Depending on climate and how often the vehicle is driven, a quality spark plug wire set will last between 30-50k miles.

• Misfires or hesitation: Rough idling, hesitation, loss of power, and occasional misfires are signs of failing spark plug wires.
• Visible Damage: Spark plug wire sets should appear clean, un-faded, with shiny connectors and malleable boots. If a spark plug wire is cracked or faded, especially around high-heat areas, it should be replaced
• Loose connections: Check both connections to make sure the metal contacts are clean and positively engaging with the distributor and the spark plugs. The boots should confidently snap onto the spark plugs.
• Increased resistance: You can test a spark plug wire for increased resistance, although due to different constructions and different resistance numbers, this can be more difficult than just replacing a spark plug wire set that is suspect or old. Carbon core resistor wires will be in the range of 4-10k ohms per foot, while spiral wound core wires will be between 50 and 500 ohms per foot, and standard copper core wires will be less than 50 ohms per foot.

About Genuine BMW

The original parts used by BMW to build your car are available as replacement parts under the “Genuine BMW” brand. When ordering a Genuine BMW part you are guaranteed to get the same part that you would pick up from your local dealerships part department. Genuine BMW parts have been built to BMW’s stringent standards and are the same quality of the original parts used to build your Ultimate Driving Machine.

You may not realize this, but the parts that make up your BMW are not necessarily manufactured by BMW. No cause for concern, as BMW designs the part, hires a manufacturer, and ensures its quality to you. In fact, many of these manufacturers have been making parts for BMW for decades. In our industry these manufacturers are called OEM (Original Equipment Manufacturers), and these are often brands you recognize, including Lemforder, ZF, Sachs, Bosch, Valeo, Zimmermann, Siemens VDO, Corteco, and more. Don’t be surprised to open that Genuine BMW parts box and find an OEM branded part inside, simply with the addition of a BMW logo.

Be sure to keep an eye out for OE tags on our product pages to quickly identify parts coming direct from OE manufacturers. That extra bit of insight could save you some serious money while shopping! Refer to our OE Academy for further information regarding the OE/OEM tags throughout the site.