Diagnosing and Replacing Ignition Coils on a 2005-2011 BMW M6
Keep your S85 V10 engine firing on all cylinders with the right ignition coils.
- The S85 V10 engine uses a special 'Ionic Current Control' system, making high-quality, compatible coils from brands like Delphi or NGK essential.
- Symptoms of failure include engine misfires, a rough idle, reduced power, and a flashing check engine light.
- Replacing all 10 coils at once is recommended for reliability, as they tend to fail around the same time.
- This is a straightforward DIY job that most owners can complete with basic tools in under two hours.
Signs of a Failing Ignition Coil in Your M6
The S85 V10 engine is a masterpiece of engineering, but it's sensitive to ignition problems. A failing coil can quickly ruin your driving experience. The most common symptom is an engine misfire, which you'll feel as a shake, shudder, or hesitation, especially at idle or under acceleration. This is often accompanied by a flashing or solid Check Engine Light. You may also notice reduced engine power, worse fuel economy, and in severe cases, the engine may stall or be difficult to start. An unburnt fuel smell from the exhaust is another sign, as a misfire allows raw fuel to pass through the engine.
Special Note on the S85 Engine
The M6's S85 engine uses a unique "Ionic Current Control" system to detect misfires instead of traditional knock sensors. This system uses the spark plugs and coils to monitor combustion in each cylinder. Because of this special design, using high-quality, compatible ignition coils is extremely important to avoid incorrect readings or fault codes.
Choosing the Right Aftermarket Ignition Coil
When replacing ignition coils on your M6, you have a choice between Original Equipment (OE) and various aftermarket brands. While Genuine BMW parts offer a guaranteed fit and performance, high-quality aftermarket options can provide similar reliability at a better price. Here’s a breakdown of available brands:
- Premium Aftermarket (OEM-Quality): Brands like Delphi, NGK, and Bremi are often Original Equipment Manufacturers for BMW and other German automakers. They produce coils to the exact specifications required by the S85's sensitive Ionic Current system. Many owners and mechanics consider these brands to be reliable, cost-effective alternatives to the dealer part.
- Standard Aftermarket: Brands like Standard Ignition (SMP) and Walker Products have a long history in the aftermarket. They offer a balance of quality and price, though owner reviews are less specific for the high-performance S85 engine compared to premium brands.
- Economy Brands: Brands like DriveWire and Global Parts typically fall into the budget category. While they offer the lowest price, their longevity and performance on a high-strung engine like the S85 are not as well-documented. For an engine this complex and powerful, investing in a proven, higher-quality coil is often recommended to avoid future issues.
Pro Tip: Replace in Sets
If one ignition coil fails and the others are original or have high mileage, it's wise to replace all 10 at once. Coils are subjected to the same heat and vibration, so when one fails, others are often not far behind. Replacing them as a set ensures balanced ignition performance and saves you from repeated repairs down the road.
Cost of Replacing BMW M6 Ignition Coils
| Part Type | Estimated Cost (Per Coil) |
|---|---|
| New OEM (Genuine BMW) | $120 - $137 |
| New Aftermarket | $35 - $118 |
| Shop Labor (Per Coil) | $42 - $61 |
Note: Costs are estimates and can vary based on location and supplier. Labor costs may be lower per coil if all are replaced at once.
Frequently Asked Questions
Is it difficult to replace the ignition coils on an M6?
No, this is a DIY-friendly job for most owners. The coils are located directly on top of the engine under plastic covers. The process involves removing the air filter boxes and engine covers, disconnecting the electrical connector, and pulling the old coil straight out. Basic tools like 8mm and 10mm sockets are all that's required.
Should I replace my spark plugs at the same time?
Yes, it is highly recommended. Worn spark plugs can put extra strain on the ignition coils, causing them to fail prematurely. Since you already have the engine covers off to access the coils, replacing the spark plugs at the same time is efficient and good preventative maintenance.
Are there any recalls for the 2005-2011 M6 ignition coils?
My search of the National Highway Traffic Safety Administration (NHTSA) database and other sources did not find any specific recalls for ignition coils on the 2005-2011 BMW M6.
What are the diagnostic codes for a bad ignition coil?
A failing ignition coil will typically cause a misfire code. The codes range from P0300 (Random/Multiple Cylinder Misfire) to P0301 through P0310, where the last digit indicates the misfiring cylinder (e.g., P0307 for cylinder 7). Specific BMW codes like 2B3B may also appear.
Technical Specifications
OEM Part Numbers: 12137841556 12137835108
Coil-on-plug 'pencil' style ignition coil, compatible with BMW's Ionic Current Control system.
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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.
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