DIY Guide: Cold Air Intake Install (BMW N20/N26 Engine)

The N20/N26 2.0L Turbo found in the F-Chassis BMWs is a capable engine, but the factory airbox is designed for silence, not flow. Upgrading to a Cold Air Intake (CAI) is the best way to hear that turbo spool and improve throttle response.

This guide applies to the F30 328i, F32 428i, and F22 228i.

Tools Required

• T20 or T25 Torx Driver (For MAF sensor screws)
• Flathead Screwdriver (For hose clamps)
• 6mm or 7mm Socket (Optional, for hose clamps)
• 10mm Socket (For strut brace bolts, if equipped)
• Clean rag (To cover the turbo inlet)

Phase 1: Removal of Stock System

Step 1: Disconnect Battery & MAF

Disconnect the Negative (-) battery terminal. Locate the MAF sensor on the intake tube near the airbox. Use a small flathead to release the grey locking tab, press down, and unplug the connector. Move the wiring harness out of the way.

Step 2: Remove the Airbox Lid

Release the four metal clips holding the airbox lid to the lower box. Loosen the hose clamp connecting the intake tube to the turbo inlet pipe (down deep near the engine). Pull the lid and tube assembly out.

Note: If you are removing the entire lower box as well (most kits require this), simply pull the bottom half of the box straight up. It is held in by rubber grommets—no bolts.

Step 3: Transfer the MAF Sensor

Using your Torx driver (T20 or T25), unscrew the two screws holding the MAF sensor into the factory tube. Carefully slide the sensor out and set it on a clean cloth. Do not reuse these screws.

Step 4: Vacuum Lines (N20 vs N26)

Check your stock intake tube. If you have an N26 engine (SULEV), you will likely see a small vacuum line connected to the side of the tube. Disconnect this line carefully. If you have a standard N20, you might not have this line.

Phase 2: Installation

Step 5: Install Heat Shield

Place the new heat shield into the engine bay. Most aftermarket shields utilize the factory rubber grommets from the bottom of the old airbox. If the grommets stuck to the old box, pull them off and push them back into the car's frame rails before dropping the new shield in.

Step 6: Install MAF into New Tube

Insert your factory MAF sensor into the new intake pipe. Orientation matters: The "open" side of the sensor bulb should face the incoming air (towards the filter). Secure it using the supplied M4 screws from your kit.

Step 7: Turbo Inlet Connection

Crucial Step: Ensure the factory turbo inlet pipe (the plastic pipe remaining on the engine) is clean and free of cracks. Slide your new silicone coupler onto this inlet pipe and tighten the clamp loosely.

Step 8: Install the Intake Tube

Lower the new intake tube into position.

• Connect the engine side to the silicone coupler.
• Connect the other end to the filter/heat shield opening.
• N26 Owners: Connect your vacuum line to the nipple on the new tube. N20 Owners: If your kit has a hole but you have no vacuum line, use the provided rubber plug to seal it.

Step 9: Filter & Final Tightening

Install the high-flow cone filter onto the end of the tube and tighten the clamp. Once the tube is aligned and not rubbing against the strut brace or radiator fan, tighten all hose clamps. Reconnect the MAF sensor plug.