BMW 740i Ignition Coil Guide (2017-2023): Symptoms, Brands, and Replacement
Fix engine misfires and rough idling in your 7-Series by choosing the right aftermarket ignition coil.
- Ignition coil failure is a common cause of misfires (P0301-P0306), rough idle, and power loss in the 740i's B58 engine.
- For best results, choose premium aftermarket brands like Bosch, Delphi, or NGK, which are often the original OEM suppliers.
- Replacement is an easy DIY job (1/5 difficulty) that takes under an hour and requires only basic tools.
- To save on future labor and ensure reliability, replace all six coils and spark plugs at the same time, especially on higher-mileage vehicles.
Is Your BMW 740i Ignition Coil Failing?
Ignition coils on the B58 engine are generally reliable, but they do fail from heat, vibration, and age. When a coil starts to go bad, it can't produce the strong spark your engine needs. This leads to noticeable problems that you shouldn't ignore.
Common Symptoms of a Bad Ignition Coil:
- Engine Misfires: This is the most common symptom. You'll feel the engine stuttering, shaking, or hesitating, especially when you accelerate or when the car is idling. A failing coil can't provide a steady spark, causing incomplete combustion in one of the cylinders.
- Rough Idle: Your 740i should idle smoothly. If you feel excessive vibration or shaking while stopped, it could be a sign that one or more ignition coils are malfunctioning.
- Check Engine Light: A misfire will almost always trigger the check engine light. If you use an OBD2 scanner, you'll likely see codes from P0300 to P0306. The last digit tells you which cylinder is misfiring (e.g., P0301 for cylinder 1).
- Loss of Power and Poor Fuel Economy: When a cylinder isn't firing correctly, your engine isn't running at full strength. You'll notice sluggish acceleration and find yourself visiting the gas station more often.
It's best not to. While the car may still run, driving with a misfire can allow unburned fuel to get into the exhaust system. This can quickly damage your expensive catalytic converter, turning a relatively small repair into a very costly one. If the check engine light is flashing, pull over and have the vehicle towed.
Choosing the Right Aftermarket Ignition Coil
When replacing an ignition coil on your 740i, you have several options. For a high-performance engine like the BMW B58, it's wise to invest in a quality part. OEM suppliers often sell the same parts under their own brand name for less than the dealer-branded part.
Brand Quality Tiers for BMW 740i
- Tier 1: OEM & Premium Aftermarket (Best Quality): Brands like Bosch, Delphi, and NGK are often the original equipment manufacturers for BMW. Eldor is another OEM supplier, though their parts are sometimes only available directly from BMW. Choosing one of these brands ensures you get a part that meets or exceeds factory specifications for performance and longevity. They are the most reliable choice for your 7-Series.
- Tier 2: Reputable Aftermarket (Good Quality): Brands such as Hitachi and Spectra offer a good balance of quality and price. They are solid replacements that provide reliable performance, though they may not have the same OEM pedigree as the top-tier brands.
- Tier 3: Budget-Friendly (Use with Caution): Brands like DriveWire, Global Parts, and Walker Products are available at a lower price point. While they can get your car running, their long-term durability on a sensitive, high-performance engine like the B58 can be a concern. They may be suitable for a quick fix but might not be the best long-term solution.
If one coil fails on a high-mileage engine (over 80,000 miles), the others are likely near the end of their life too. It's highly recommended to replace all six ignition coils at the same time. This prevents you from having to do the same job again in a few months and ensures consistent performance across all cylinders. It's also the perfect time to replace your spark plugs.
Cost to Replace 2017-2023 BMW 740i Ignition Coils
The cost can vary based on the parts you choose and whether you do the work yourself. The job is simple enough for most DIY mechanics.
| Item | Cost Range | Notes |
|---|---|---|
| New Aftermarket Ignition Coil (Single) | $33 - $98 | Price depends on the brand. Premium brands are at the higher end. |
| New OEM Ignition Coil (Single) | $70 - $150 | Purchased from a BMW dealership. |
| Shop Labor Cost | $100 - $250 | An independent shop will typically charge for about 1 hour of labor. Dealer labor rates will be higher. |
| DIY Savings | $100 - $250 | You save on labor costs. The job requires only basic tools and takes less than an hour. |
Frequently Asked Questions
Should I replace all six ignition coils at once?
Yes, it is highly recommended, especially if your vehicle has over 80,000 miles. Coils are exposed to the same conditions, so when one fails, others are likely to follow soon. Replacing them all at once saves you from repeated labor and ensures consistent engine performance.
Is it difficult to replace the ignition coils on a 740i myself?
No, this is a very DIY-friendly job. The ignition coils are located directly on top of the engine and are easily accessible after removing the engine cover. The process involves disconnecting a wire, removing one bolt, and pulling the old coil out. It requires basic hand tools and can be completed in under an hour.
What's the difference between OEM and a premium aftermarket coil from Bosch or NGK?
Often, there is no functional difference. Brands like Bosch, Delphi, and NGK are frequently the original equipment manufacturers (OEM) for BMW. This means they produce the exact same part sold at the dealership, but it comes in their own packaging and usually costs less.
Do I need to replace my spark plugs at the same time?
It is a very good idea. You have to remove the ignition coils to access the spark plugs anyway, so you save on future labor. Worn spark plugs can also put extra strain on new ignition coils, potentially causing them to fail prematurely.
Are there any recalls for the 2017-2023 BMW 740i ignition coils?
As of early 2026, there are no specific recalls for ignition coil failure on the 2017-2023 BMW 740i. There was a recall for some 2020-2021 740i models related to the engine starter, but not the ignition coils. Always check the NHTSA website with your VIN for the most up-to-date recall information.
Technical Specifications
OEM Part Numbers: 12138643360
Coil-on-plug design, one per cylinder. The 2017-2023 BMW 740i uses the B58 6-cylinder engine and requires six ignition coils.
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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 740i: