BMW Spark Plug Replacement Guide
Does your BMW have a rough idle, difficulty starting, engine misfiring, and the check engine light is on? Learn how to fix it by replacing your BMW’s spark plugs.
Follow the procedures below. This information should be helpful to owners of the BMW 1, 3, 5, 6, 7, X1, X3, and X5 series BMW 1, 3, 5, 6, 7, X1, X3, and X5 series since BMW uses the same engine across many models.
How to Replace BMW Spark Plug
Symptoms
What you may notice if your BMW spark plugs are worn out or not replaced at the recommended interval.
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- Rough idle
- Hard starting
- Engine judder (misfire)
- Power loss
- “Check Engine” light on
- High fuel consumption
What will you need
- BMW spark plugs
- NGK OEM3199 Laser is a popular choice, along with Bosch OEM 158253 FR7NP.
- New Ignition coils (optional)
- Connector rubber boots (when applicable, for engines up to 2004.)
- 14mm or 5/8 deep hex socket (for all engines except direct injection)
- 14mm thin wall bi-hex socket with wobble function (for direct injection engines)
- 3/8 long extension
- 3/8″ Ratchet
- 3/8″ Torque wrench
- 3/8 or 9mm rubber hose, 1/2 feet long (highly recommended)
- 8mm socket
- 10mm socket
- Phillips and flathead screwdrivers
- Silicon grease (recommended for connector rubber boots)
How to Change BMW Spark Plugs
- Turn the ignition OFF and open the hood.
- To access the spark plugs at the rear of the engine, remove the drain tray installed below the windshield. On some models, a strut brace is installed over the engine. It can be removed to gain better access, but it is unnecessary.
- Remove the engine cover. If it is held in place with screws, unscrew them. If there are no screws visible, pull the cover off.
- The ignition coil is a connector secured in position by a retaining clip. Carefully unlock the retaining clip and unplug the ignition coil wiring harness.
- Pull the ignition coil out. If it is stuck, do not use excessive force. You might break it, or the silicon insulator might come off. Wiggle it a bit and twist it back and forth while pulling it out simultaneously until it ‘pops out.’
- Older engines have ignition coils with detachable connector rubber boots. If your engine has these, they will likely detach from the ignition coil when you pull. You will need to pull them out separately.
- If you are reusing ignition coils, inspect them for cracks or contamination. If you spot any of these, do not reuse them.
- Visually inspect the spark plug hole for debris or oil. If there is any, clean it before taking the spark plug out. Take extra caution, as any debris left might fall into the cylinder when the spark plug is removed.
- Using an appropriate socket, extension, and ratchet, undo the spark plug and carefully pull it out of the plughole.
- Visually inspect the spark plug. It can tell you a lot about the state of the engine and that cylinder in particular.
- Push the upper side of the spark plug into the 3/8″ rubber hose. Using a 3/8″ rubber hose as a hand tool, screw the sparks plug hand-tight into the cylinder head plug thread as far as it will go.
- Tighten spark plugs to the specified torque using a torque wrench, extension, and appropriate socket.
- Renew the boots on engines with ignition coils and detachable connector rubber boots. Before reinstalling, apply a small amount of silicone grease to the inner spark plug side of the boot.
- Reinstall the ignition coil assembly. Push it onto the spark plug until you hear a ‘pop.’
- Connect the wiring harness to the ignition coil and lock the retaining clips. Double-check the connector for looseness. Reinstall the engine cover, scuttle drain, and any other parts in reverse order to install.
- Start your BMW engine and observe how it operates.
- Reset the spark plug reminder via the instrument cluster.
Check Engine Light Still On
If the check engine light is still on after you replaced the spark plugs, you can use the YOUCANIC Full System Scanner to clear the stored codes on your BMW. This scanner can also read and clear fault codes through every control module of your vehicle.
Hints
- Traces of engine oil on the ignition coil boot indicate a leaking valve cover (cam cover) gasket. Oil is very aggressive on silicon boot insulation, so thecam cover seal must be renewed before reinstalling ignition coils.
- Spark plug holes are deep and usually under an angle. Access to some parts of the engine can be limited. This means you can easily cross-thread the new spark plugs while installing them. To prevent this, use a rubber hose as a flexible tool that will allow you to install the spark plug safely. This way, the rubber hose will slip if the plug starts to cross-thread.
Recommended BMW Spark Plug Replacement Interval
Spark plugs and ignition coils are key engine components in your BMW, so you need to make sure that they are in good shape.
Usual intervals for preventive spark plug and ignition coil replacement are:
- 60.000 miles for naturally aspirated engines before 1999
- 100.000 miles for newer naturally aspirated engines
- 40.000 miles for all turbocharged engines
Yet, it is possible to have problems with spark plugs before this interval. This can be caused by poor-quality fuel, high oil consumption, or fuel injection system-related problems. Also, ignition coils can fail due to damage or deterioration.
What size are BMW Spark Plugs?
On most BMW engines, a 14mm hex-deep or 5/8-deep socket is suitable. However, if the engine has direct injection, a thin-walled bi-hex socket with a wobble function is required.
Recommended BMW Spark Plug Torque
The majority of BMW engines use spark plugs with M14 x 1.25 threads. The recommended tightening torque for most BMW spark plugs is 30Nm.
Always call your local dealer to verify your BMW engine’s correct spark plug torque. Your dealer can look up the correct torque if you provide the VIN. The price is per one spark plug or ignition coil. You will need as many spark plugs or ignition coils as the number of cylinders in your BMW. Typically, four, six, or eight.
Frequently Asked Questions
BMW won’t start after the spark plug change?
If your BMW cranks and doesn’t start, either coils or connectors may be loose. Spark plugs that are not tightened enough can also cause this. Also, incorrect plugs could be a cause, so double-check that as well.
If your BMW does not crank, you might have a weak battery.
Also, a scan tool is used to check if any errors are stored.
What is the average life of BMW spark plugs?
It varies from 60,000 miles on older engines to 100,000 miles on newer generations. However, spark plugs should be changed every 40,000 miles on new turbocharged engines. Poor-quality fuel, oil consumption, or problems with fuel injection systems can shorten spark plug lifespan.
Recommended BMW spark plug gap?
Spark plugs for your BMW come with a preset gap. So, there is no need to adjust the gap.
What are the best BMW spark plugs?
OEM spark plugs are a good choice for factory-tuned BMW. They are tailored exactly for your engine type and are not expensive. Aftermarket brands like NGK, Bosch, or Denso can also be used. In that case, make sure you have your engine’s exact type.
Conclusion
Changing ignition coils every time you change the spark plugs is unnecessary. Check the body, connector, and insulation for cracks and traces of contamination. If there is any doubt, replacing them with a new one is better. They can fail without any prior warning signs. And they are not too expensive.
Changing spark plugs and ignition coils on most BMW engines is straightforward. All you need is a basic set of tools and some elbow grease. This is a great job for a novice DIYer looking for experience.
We hope you find the BMW Spark Plug Replacement Guide helpful. Check these troubleshooting and repair guides for more help on your BMW.
