Spark Plug Replacement – BMW B46 Turbo 4-Cylinder Engine

August 21, 2023

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Spark Plug Replacement – BMW B46 Turbo 4-Cylinder Engine

This repair procedure gives step by step instructions on installing new spark plugs in the BMW B46 turbocharged 4-cylinder engine. We recommend the spark plugs 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, engine stall, poor performance, engine won't start

This repair can be used on the following BMW models:

2013

225i Active Tourer, Cooper S 3 doors,

2014

220i Active Tourer, 220i Gran Tourer, 225i Active Tourer, 225iX Active Tourer, 320i Touring, 320iX Touring, 330i Touring, 730Li Sedan, 730i Sedan, Cooper S 3 doors, Cooper S 5 doors, Cooper S Clubman, Cooper S Convertible, JCW 3 doors, X1 20Li SUV, X1 20LiX SUV, X1 20i SUV, X1 20iX SUV, X1 25LiX SUV, X1 25iX SUV, X1 28i SUV, X1 28iX SUV,

2015

2016

120i 3 doors, 120i 5 doors, 120i Sedan, 125i 3 doors, 125i 5 doors, 125i Sedan, 220i Active Tourer, 220i Convertible, 220i Coupe, 220i Gran Tourer, 225i Active Tourer, 225iX Active Tourer, 230i Convertible, 230i Coupe, 230iX Convertible, 230iX Coupe, 320Li Sedan, 320LiX Sedan, 320i Gran Turismo, 320i Touring, 320iX Gran Turismo, 320iX Touring, 330Li Sedan, 330LiX Sedan, 330e Sedan, 330i Gran Turismo, 330i Sedan, 330i Touring, 330iX Gran Turismo, 330iX Sedan, 330iX Touring, 420i Convertible, 420i Coupe, 420i Gran Coupe, 420iX Coupe, 420iX Gran Coupe, 430i Convertible, 430i Coupe, 430i Gran Coupe, 430iX Convertible, 430iX Coupe, 430iX Gran Coupe, 520i 1.6 Sedan, 520i Sedan, 520i Touring, 525Li Sedan, 528Li Sedan, 530Le Sedan, 530Li Sedan, 530LiX Sedan, 530e Sedan, 530eX Sedan, 530i Sedan, 530i Touring, 530iX Sedan, 530iX Touring, 630i Gran Turismo, 730Li Sedan, 730i Sedan, 740Le Sedan, 740LeX Sedan, 740e Sedan, 740eX Sedan, Cooper S ALL4 Clubman, Cooper S ALL4 Countryman, Cooper S 3 doors, Cooper S 5 doors, Cooper S Clubman, Cooper S Convertible, Cooper S Countryman, JCW ALL4 Clubman, JCW ALL4 Countryman, JCW 3 doors, JCW Convertible, X1 20Li SUV, X1 20LiX SUV, X1 20i SUV, X1 20iX SUV, X1 25LiX SUV, X1 25iX SUV, X1 28i SUV, X1 28iX SUV, X2 20i SAC, X2 28iX SAC, X3 20i 1.6 SUV, X3 20i SUV, X3 20iX (TR51) SUV, X3 30iX (TR91) SUV, X3 30iX (TR92) SUV, X3 30iX SUV,

2017

120i 3 doors, 120i 5 doors, 120i Sedan, 125i 3 doors, 125i 5 doors, 125i Sedan, 220i Active Tourer, 220i Convertible, 220i Coupe, 220i Gran Tourer, 225i Active Tourer, 225iX Active Tourer, 230i Convertible, 230i Coupe, 230iX Convertible, 230iX Coupe, 320Li Sedan, 320LiX Sedan, 320i Gran Turismo, 320i Sedan, 320i Touring, 320iX Gran Turismo, 320iX Touring, 330Li Sedan, 330LiX Sedan, 330e Sedan, 330i Gran Turismo, 330i Sedan, 330i Touring, 330iX Gran Turismo, 330iX Sedan, 330iX Touring, 420i Convertible, 420i Coupe, 420i Gran Coupe, 420iX Coupe, 420iX Gran Coupe, 430i Convertible, 430i Coupe, 430i Gran Coupe, 430iX Convertible, 430iX Coupe, 430iX Gran Coupe, 520i 1.6 Sedan, 520i Sedan, 520i Touring, 525Li Sedan, 528Li Sedan, 530Le Sedan, 530Li Sedan, 530LiX Sedan, 530e Sedan, 530eX Sedan, 530i Sedan, 530i Touring, 530iX Sedan, 530iX Touring, 630i Gran Turismo, 730Li Sedan, 730i Sedan, 740Le Sedan, 740LeX Sedan, 740e Sedan, 740eX Sedan, Cooper S ALL4 Clubman, Cooper S ALL4 Countryman, Cooper S 3 doors, Cooper S 5 doors, Cooper S Clubman, Cooper S Convertible, Cooper S Countryman, JCW ALL4 Clubman, JCW ALL4 Countryman, JCW 3 doors, JCW Convertible, X1 20Li SUV, X1 20LiX SUV, X1 20i SUV, X1 20iX SUV, X1 25LiX SUV, X1 25iX SUV, X1 28i SUV, X1 28iX SUV, X2 20i SAC, X2 20iX SAC, X2 25iX SAC, X2 28i SAC, X2 28iX SAC, X2 M35iX SAC, X3 20i (TR12) SUV, X3 20i (TR16) SUV, X3 20i 1.6 SUV, X3 20i SUV, X3 20iX (TR51) SUV, X3 20iX (TR52) SUV, X3 20iX (TR55) SUV, X3 20iX (TR56) SUV, X3 25iX SUV, X3 28iX SUV, X3 30i SUV, X3 30iX (TR91) SUV, X3 30iX (TR92) SUV, X3 30iX (TR95) SUV, X3 30iX (TR96) SUV, X3 30iX SUV, X4 20iX SAC, X4 30iX SAC, Z4 20i Roadster, Z4 30i Roadster,

2018

120i 3 doors, 120i 5 doors, 120i Sedan, 125i 3 doors, 125i 5 doors, 125i Sedan, 220i Active Tourer, 220i Convertible, 220i Coupe, 220i Gran Tourer, 225i Active Tourer, 225iX Active Tourer, 228iX Gran Coupe, 230i Convertible, 230i Coupe, 230iX Convertible, 230iX Coupe, 320Li Sedan, 320LiX Sedan, 320i 1.6 Sedan, 320i Gran Turismo, 320i Sedan, 320i Touring, 320iX Gran Turismo, 320iX Sedan, 320iX Touring, 325Li Sedan, 325LiX Sedan, 325i Sedan, 330Li Sedan, 330LiX Sedan, 330e Sedan, 330i Gran Turismo, 330i Sedan, 330i Touring, 330iX Gran Turismo, 330iX Sedan, 330iX Touring, 420i Convertible, 420i Coupe, 420i Gran Coupe, 420iX Coupe, 420iX Gran Coupe, 430i Convertible, 430i Coupe, 430i Gran Coupe, 430iX Convertible, 430iX Coupe, 430iX Gran Coupe, 520i 1.6 Sedan, 520i Sedan, 520i Touring, 525Li Sedan, 530Le Sedan, 530Li Sedan, 530LiX Sedan, 530e Sedan, 530eX Sedan, 530i Sedan, 530i Touring, 530iX Sedan, 530iX Touring, 630i Gran Turismo, 730Li Sedan, 730i Sedan, 740Le Sedan, 740LeX Sedan, 740e Sedan, 740eX Sedan, Cooper S ALL4 Clubman, Cooper S ALL4 Countryman, Cooper S 3 doors, Cooper S 5 doors, Cooper S Clubman, Cooper S Convertible, Cooper S Countryman, JCW ALL4 Clubman, JCW ALL4 Countryman, JCW 3 doors, JCW Convertible, M135iX 5 doors, M235iX Gran Coupe, X1 20Li SUV, X1 20LiX SUV, X1 20i SUV, X1 20iX SUV, X1 25Li SUV, X1 25LiX SUV, X1 25iX SUV, X1 28i SUV, X1 28iX SUV, X2 20i SAC, X2 20iX SAC, X2 25i SAC, X2 25iX SAC, X2 28i SAC, X2 28iX SAC, X2 M35iX SAC, X3 20i (TR12) SUV, X3 20i (TR16) SUV, X3 20i 1.6 SUV, X3 20i SUV, X3 20iX (TR51) SUV, X3 20iX (TR52) SUV, X3 20iX (TR55) SUV, X3 20iX (TR56) SUV, X3 20iX SUV, X3 25iX SUV, X3 28iX SUV, X3 30eX SUV, X3 30i SUV, X3 30iX (TR91) SUV, X3 30iX (TR92) SUV, X3 30iX (TR95) SUV, X3 30iX (TR96) SUV, X3 30iX SUV, X4 20iX SAC, X4 30iX SAC, X5 30iX SUV, X6 30iX SAC, Z4 20i Roadster, Z4 30i Roadster,

2019

120i 3 doors, 120i 5 doors, 120i Sedan, 125i 3 doors, 125i 5 doors, 220i Active Tourer, 220i Convertible, 220i Coupe, 220i Gran Tourer, 225i Active Tourer, 225iX Active Tourer, 228iX Gran Coupe, 230i Convertible, 230i Coupe, 230iX Convertible, 230iX Coupe, 320Li Sedan, 320LiX Sedan, 320i 1.6 Sedan, 320i Gran Turismo, 320i Sedan, 320i Touring, 320iX Gran Turismo, 320iX Sedan, 320iX Touring, 325Li Sedan, 325LiX Sedan, 325i Sedan, 330LiX Sedan, 330e Sedan, 330i Gran Turismo, 330i Sedan, 330i Touring, 330iX Gran Turismo, 330iX Sedan, 330iX Touring, 420i Convertible, 420i Coupe, 420i Gran Coupe, 420iX Coupe, 420iX Gran Coupe, 430i Convertible, 430i Coupe, 430i Gran Coupe, 430iX Convertible, 430iX Coupe, 430iX Gran Coupe, 520i 1.6 Sedan, 520i Sedan, 520i Touring, 525Li Sedan, 530Le Sedan, 530Li Sedan, 530LiX Sedan, 530e Sedan, 530eX Sedan, 530i Sedan, 530i Touring, 530iX Sedan, 530iX Touring, 630i Gran Turismo, 730Li Sedan, 730i Sedan, 740Le Sedan, 740LeX Sedan, 740e Sedan, 740eX Sedan, Cooper S ALL4 Clubman, Cooper S ALL4 Countryman, Cooper S 3 doors, Cooper S 5 doors, Cooper S Clubman, Cooper S Convertible, Cooper S Countryman, JCW ALL4 Clubman, JCW ALL4 Countryman, JCW 3 doors, JCW Convertible, M135iX 5 doors, M235iX Gran Coupe, X1 20Li SUV, X1 20LiX SUV, X1 20i SUV, X1 20iX SUV, X1 25Li SUV, X1 25LiX SUV, X1 25iX SUV, X1 28i SUV, X1 28iX SUV, X2 20i SAC, X2 20iX SAC, X2 25i SAC, X2 25iX SAC, X2 28i SAC, X2 28iX SAC, X2 M35iX SAC, X3 20i (TR12) SUV, X3 20i (TR16) SUV, X3 20i 1.6 SUV, X3 20i SUV, X3 20iX (TR51) SUV, X3 20iX (TR52) SUV, X3 20iX (TR55) SUV, X3 20iX (TR56) SUV, X3 20iX SUV, X3 25iX SUV, X3 28iX SUV, X3 30eX SUV, X3 30i SUV, X3 30iX (TR91) SUV, X3 30iX (TR92) SUV, X3 30iX (TR95) SUV, X3 30iX (TR96) SUV, X3 30iX SUV, X4 20iX SAC, X4 30iX SAC, X5 30iX SUV, X6 30iX SAC, Z4 20i Roadster, Z4 30i Roadster,

2020

320i Sedan, 330e Sedan, 520i Sedan, 630i Gran Turismo, 730Li Sedan, 730i Sedan, X1 20i SUV, X1 20iX SUV,

Advanced level repair.

Step 1 - Purchase Parts

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

Spark Plug

Just like with engine oil, the great debate continues about which is the best spark plug to use in your BMW. We believe the best plug is a factory Genuine BMW plug. Factory plugs give you the confidence that you are installing the same part that the vehicle was delivered from the factory with.

14mm Spark Plug Tool with Magnetic Swivel

Removing spark plugs with a rigid, none-magnetic socket wrench is not only tedious but can actually cause damage to your vehicle's engine. This socket wrench holds on firmly to the spark plug with its super strong magnetic tip. Its 360 degree of swivel makes it easy to remove spark plugs buried under parts or located close to the firewall in the rear of the engine. A necessity for every professional and home mechanic.

Spark Plug Installation Tool

Professional mechanics know that only a darn fool drops a spark plug into a cylinder head tube when installing a new one. Dropping a plug down its tube can cause the plug gap to be bent causing a rough idling engine. This rubber spark plug installation tool safely threads the new plug into the head. Using this tool is cheap insurance against damaged plugs, cross threading and potential engine damage.

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. .

You must remove the ignition coils before starting this repair!

Please see our article Ignition Coil Replacement - B46 Turbo 4-Cylinder Engine for instructions on removing the ignition coils.

1. Removing and installing spark plugs.

Spark Plug Replacement – BMW B46 Turbo 4-Cylinder Engine

Click to enlarge image

- The best tool for removing spark plugs from the B46 engine is a 3/8" ratchet with an extension and magnetic spark plug socket. This will help avoid breaking the spark plug off inside the tube.

Click to enlarge image

- Using a 14mm magnetic swivel spark plug socket, remove the spark plug 12120040551 from the cylinder head.

View part diagram for this step

Pro Tip

Avoid "dropping" the spark plug into the tube when reinstalling a fresh one. This can throw off the gap at the end of the plug causing your engine to run rough!

Click to enlarge image

- The best tool for installing a spark plug is a rubber spark plug installation tool. It helps avoid cross-threading the spark plug into the cylinder head and is much easier to use than a swivel head socket.

Click to enlarge image

- Intsall a new spark plug 12120040551. Torque the spark plug to 30 Nm (22 ft-lb).

View part diagram for this step

Replace the ignition coils.

Please see our article Ignition Coil Replacement - B46 Turbo 4-Cylinder Engine for instructions on replacing the ignition coils.