How To Diagnose And Replace Bad Ignition Coils On Your BMW?

　　What are the symptoms of a broken ignition coil?

　　Engine misfire

　　Rough

　　power failure

　　Reduce fuel economy

　　Stop in extreme cases

　　Check engine light

　　Car won't start

　　Ignoring these signs usually only leads to distress. Whether it just uses more fuel than usual, or it means your car refuses to start and is stuck in the parking lot.

　　The service life of BMW ignition coils can reach more than 140,000 miles. They are usually replaced only when there are signs of failure, not as preventive maintenance.

　　How long does it take to replace the ignition coil?

　　If you are an avid DIY enthusiast, depending on the car, this work can be completed in 2 hours. When replacing the ignition coil, we recommend that you check and replace the spark plug at the same time.

　　How much does it cost to replace the ignition coil?

　　If you plan to drive your car to a dealership to complete this work, you will spend $700. Buying parts through us and doing the work yourself, you only pay a small portion of the cost. In addition, when you need to replace them again, you can use our lifetime replacement guarantee.

　　Tools required for diagnosis and replacement of BMW ignition coils:

　　OBDII scanning tool (optional)

　　LED light under the hood (optional)

　　Screwdriver set (optional)

　　Dielectric Grease

　　Parts required for diagnosis and replacement of BMW ignition coils:

　　BMW ignition coil kit (6 sets for vehicles with 6-cylinder engine)

　　BMW ignition coil kit (4 sets for vehicles with 4-cylinder engine)

　　BMW ignition coil

　　Step 1: Diagnose

　　In our case, the diagnosis is simple. Our F30 BMW has a check engine light, and the idling speed is obviously rough. If the cylinder misfires, the engine light should be turned on. If you have a scanning tool (if you own any OBDII cars, we strongly recommend that you use it), now is the time for you to plug it in to check which cylinder is misfired. On our BMW, our scanner showed that we had a misfire on the No. 1 cylinder. If you are using a scanning tool, you can skip to step 5.

　　Step 2: Remove the engine cover

　　First remove the engine cover and anything obstructing access to the injector. Since these injectors are suitable for various BMW models, the process is different for everyone.

　　Step 3: Disconnect one coil at a time

　　When the car is running, disconnect the wiring from the ignition coil of the cylinder No. 1 and listen to the sound changes when idling. If the sound does not change significantly, you know that the problem is cylinder number one. If there is a significant change in the sound or the operation of the engine, you know that it is a cylinder, not the number one cylinder. If this is the case, please continue offline until you find the problem cylinder.

　　Step 4: Remove and alternate coil

　　Once you have determined which ignition coil is the potential culprit, you can confirm this by replacing the coil with a coil that you know is functioning properly. Putting a mark on the bad coil will make your life easier, because you can easily forget which cylinder to move it to.

　　Step 5: Check the coil sheath

　　When you alternate ignition coils, you might as well check the boots for defects. Even the smallest holes or tears can cause grounding problems-making the ignition coil ineffective. On our BMW, the coil of the No. 1 cylinder has a pinhole in the trunk. Since you are already here, we recommend that you purchase a car-specific kit and replace all ignition coils at the same time.

　　Step 6: Install the new coil and reassemble

　　Whether you are replacing one coil or all coils, the process is fast and simple. Apply a very small amount of dielectric grease to the inside of the coil sheath; this will make them easier to remove in the future. From this point on, you only need to install the coil on the plug, reconnect the wiring, and reinstall the hood.