Home 3 Series 2019-Present (G20,G21) Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine

Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine

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Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine

This repair procedure gives step by step instructions on installing new ignition coils in the BMW B46 turbocharged 4-cylinder engine. We recommend the ignition coils be replaced in the B46 engine every 60,000 to keep it running at peak performance. Please click on the button below to see all BMW models that this repair applies to.
Not sure which engine you have in your BMW? Use our engine finder tool to easily identify it!
Possible Symptoms: Rough idle, lack of power, engine stalls, engine wont start
This repair can be used on the following BMW models:
Advanced level repair.

Step 1 - Purchase Parts

You will need the following parts and supplies to perform this repair.

Ignition Coil

We have long ago established here at the Repair Guide that when it comes to engine electronics, the best practice is to stay away from aftermarket parts. The same holds true with coils. Some manufacturers may claim they are "OEM", but in the end the only way you know you are getting factory quality is to install Genuine BMW. These are the same factory ignition coils that would be installed at the dealership.

Step 2 - Repair Procedure

Unless otherwise noted, all vehicle repair step images in this article are copyrighted, and used courtesy of BMW of North America, Inc. .
1. Remove the right cover in the engine compartment
Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine
Click to enlarge image

- Remove the top fasteners (1).

- Unlock the latching mechanism (3).

- Remove the cover (2).

View part diagram for this step

2. Remove the left cover in the engine compartment
Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine
Click to enlarge image

- Remove the top fasteners (1).

- Unlock the latching mechanism (3).

- Remove the cover (2).

View part diagram for this step
Technical Information

In the next step the front strut brace is removed. The front strut brace is an integral part of the vehicle's suspension and must be reinstalled correctly.

3. Remove the strut brace
remove the strut brace
Click to enlarge image

Unsnap the top cover. Remove the two anchor bolts (1).

Remove the two bolts anchoring the strut to the body of the vehicle (2).

Remove the strut brace.

View part diagram for this step
4. Remove the center bulkhead sound insulation
detach the positive battery cable and remove the engine sealing gasket
Click to enlarge image

- Detach the positive battery cable from the sealing gasket (2).

- Remove the anchor rivet (1).

- Remove the sealing gasket in the direction shown in image (2).

Technical Information

Be careful when removing the acoustic engine cover. They are prone to breaking when excessive force is applied. Try and pull the cover loose close to the mounting points, not along the edges.

5. Remove the acoustic engine cover
Remove the acoustic cover from the engine
Click to enlarge image

- Pull the acoustic engine cover loose from the mounting points as shown in the image and remove from the vehicle.

View part diagram for this step
6. Remove the coils
Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine
Click to enlarge image

- Unlock and remove the electrical connector (1).

- Remove mounting bolt (2).

- Grasp the ignition coil and remove it from the engine (3).

- Repeat for other three coils.

View part diagram for this step
7. Install new ignition coils
Ignition Coil Replacement – BMW B46 Turbo 4-Cylinder Engine
Click to enlarge image

Part Needed - 4 x ignition coil 12138643360

- Install a new ignition coil 12138643360 in the engine.

- Install the mounting bolt (2) and torque to 8Nm (6 ft-lb).

- Reconnect the electrical plug (1).

View part diagram for this step
Pro Tip

If you are having issues reinstalling the acoustical engine cover, try coating the rubber mounts with a thin layer of liquid detergent like Dawn. This will help the cover slip easily back onto its mounts.

8. Reinstall Parts

- Reinstall the parts following steps 1-5 above in reverse.

- Strut brace mounting bolts torque to 56Nm (41 ft-lb).

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