Ignition Coil Guide for the 2012-2018 BMW 640i (F12/F13)
Engine misfiring or running rough? This guide will help you diagnose and choose the right replacement ignition coils for your N55-powered 640i.
- Stick with OEM-supplier brands like Bosch, Delphi, or Eldor for the best reliability and performance.
- It is highly recommended to replace all six coils and spark plugs at the same time to prevent future issues.
- A failing ignition coil will cause misfires, a rough idle, and will trigger the check engine light with codes P0301-P0306.
- This is a simple DIY replacement that requires basic tools and can be completed in under an hour.
Is Your BMW 640i Stumbling? It Could Be the Ignition Coils
Ignition coils are a common wear item on many modern engines, including the N55 engine in your 2012-2018 BMW 640i. When a coil starts to fail, it can't deliver the strong electrical pulse needed for proper combustion. This often leads to noticeable engine problems that can disrupt your car's smooth performance.
Symptoms of a Failing Ignition Coil
A bad ignition coil isn't always a complete failure. It might work intermittently at first, making diagnosis tricky. Look out for these common signs:
- Engine Misfires: The most common symptom. You'll feel a shudder, stumble, or hesitation from the engine, especially during acceleration.
- Rough Idle: The engine may shake or vibrate more than usual when the car is stopped.
- Check Engine Light: A failing coil will almost always trigger a Check Engine Light. Common codes include P0300 (random misfire) or P0301 through P0306, which point to a misfire in a specific cylinder (e.g., P0306 is cylinder 6).
- Reduced Power and Fuel Economy: When a cylinder isn't firing correctly, your engine loses power and has to work harder, burning more fuel.
- "Drivetrain Malfunction" Warning: Your iDrive screen may display this message when a misfire is detected.
Known Issues and Technical Service Bulletins (TSBs)
For the N55 engine in your 640i, BMW issued a Technical Service Bulletin (SI B12 15 15) regarding corrosion on the metal heat shield of the Delphi ignition coils. The bulletin states that moisture can enter the spark plug area and cause surface corrosion on the coil's casing. However, BMW clarifies that this corrosion does not affect the coil's function or performance, and the part should not be replaced for this reason alone. No safety recalls have been issued by the NHTSA for ignition coils on the 2012-2018 BMW 640i.
Choosing the Right Aftermarket Ignition Coil for Your 640i
When shopping for new ignition coils, you'll find several brands. For a high-performance car like a BMW, the quality of ignition components matters. Here’s a breakdown of your options, from best to budget.
Tier 1: OEM-Supplier Brands
These brands are the original manufacturers for BMW. They offer the same quality as the part you'd buy at a dealership, but without the BMW logo and associated markup. For the N55 engine, the primary OEM suppliers are Bosch and Delphi. Some forum users note that BMW switched from Bosch to Delphi due to premature failures on the original Bosch coils, making Delphi the revised and often recommended part. However, both brands are considered top-tier choices.
- Bosch: A long-time OEM for BMW. Widely available and trusted.
- Delphi: The revised OEM part for many N55 engines, often recommended by dealerships and enthusiasts.
- Eldor: Another OEM supplier that started appearing on later model BMWs (around 2016 and up) and is considered an excellent alternative to Bosch or Delphi. 🎬 See a detailed review of the best N55 ignition coil options.
Tier 2: Reputable Aftermarket Brands
These companies are well-known in the auto parts industry for producing reliable components. They are a solid choice if OEM-supplier parts aren't available or if you're looking for a balance of quality and price.
- NGK: Famous for spark plugs, NGK also manufactures high-quality ignition coils that are a popular choice for many imports.
- Standard Ignition (SMP): A respected brand that produces a wide range of reliable engine management components.
- Hitachi: A Japanese manufacturer known for high-quality electronics and engine parts.
Tier 3: Budget-Friendly Brands
Brands like DriveWire, Global Parts, and True Tech fall into this category. While their low price is attractive, their long-term reliability and performance may not match the standards of the higher-tier brands. These could be a viable option if you are on a tight budget or planning to sell the vehicle soon, but for long-term ownership, investing in an OEM-supplier or reputable aftermarket brand is recommended.
Pro Tip: Replace in Sets
If one ignition coil has failed due to age and mileage, the others are likely not far behind. Coils are subjected to the same heat and vibration, causing them to wear out at a similar rate. To save time and prevent future misfires, it is highly recommended to replace all six ignition coils at the same time. It's also best practice to replace your spark plugs during the job, as worn plugs can strain the new coils.
Expected Costs for Ignition Coil Replacement
| Part Type | Price Range (Set of 6) | Notes |
|---|---|---|
| New OEM (Dealer) | $440 - $600 | Genuine BMW-branded parts from a dealership. |
| New Aftermarket (OEM Supplier) | $170 - $240 | Bosch, Delphi, or Eldor brands. This is the recommended sweet spot for quality and value. |
| New Aftermarket (Budget) | $120 - $180 | Lower-cost brands. Quality and longevity can be inconsistent. |
| Shop Labor | $100 - $200 | This is a quick job for an experienced mechanic. |
Frequently Asked Questions
Should I replace all six ignition coils at once?
Yes. Ignition coils wear at a similar rate. If one has failed, the others may fail soon after. Replacing them all at once saves you from repeated repairs and ensures consistent engine performance.
Do I need to replace my spark plugs with my ignition coils?
It is strongly recommended. Worn spark plugs have a wider gap, which forces the ignition coil to produce a higher voltage to create a spark. This extra strain can shorten the life of your new coils. Since you already have the engine cover off, it's the perfect time to do both jobs.
🎬 Learn how to replace both spark plugs and coils yourself.What's the difference between a "Genuine BMW" coil and an OEM-supplier coil like Bosch or Delphi?
The only significant difference is the box and the price. Bosch and Delphi are the companies that BMW pays to manufacture their coils. Buying the Bosch or Delphi branded part gives you the same quality without paying for the BMW logo.
Is replacing the ignition coils a DIY job?
Yes, for most home mechanics this is a very straightforward job. It requires basic tools, involves removing the engine cover, unplugging the electrical connector, and pulling the old coil straight out. The entire job for all six coils can typically be done in under an hour.
🎬 Watch this step-by-step guide on replacing your 6-series ignition coils.Helpful Videos
Technical Specifications
OEM Part Numbers: 12138616153 12137594937 12138657273 12137562744 12137571643
Coil-on-plug design, one required per cylinder. Total of six for the BMW 640i N55 engine.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- BMW 640i:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your BMW 640i Stumbling? It Could Be the Ignition Coils
- Symptoms of a Failing Ignition Coil
- Known Issues and Technical Service Bulletins (TSBs)
- Choosing the Right Aftermarket Ignition Coil for Your 640i
- Tier 1: OEM-Supplier Brands
- Tier 2: Reputable Aftermarket Brands
- Tier 3: Budget-Friendly Brands
- Pro Tip: Replace in Sets
- Expected Costs for Ignition Coil Replacement
- Frequently Asked Questions
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