🔧 GLA - Cabin Air Filter Replacement

The cabin air filter cleans the air entering your A/C and heater. Replacing it restores airflow, reduces musty smells, and helps keep dust/pollen out of the cabin.

Difficulty Level: Beginner | Estimated Time: 0.5-1.0 hours

Assumption: Your GLA uses the passenger-side (under-glovebox) cabin filter access.

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⚠️ Safety & Precautions

• ⚠️ Turn ignition OFF and keep the key/fob away from the vehicle.
• ⚠️ Work carefully around the passenger knee/airbag areas—don’t probe wiring or yellow connectors.
• ⚠️ Use safety glasses; dust and debris can fall when the cover opens.
• ⚠️ Battery disconnect is not required for this job.

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🔧 Required Tools

You'll need the following tools for this repair:

• Torx T20 screwdriver
• Trim removal tool (plastic)
• Small flat-blade screwdriver
• Flashlight
• Shop vacuum with crevice tool
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Cabin air filter (dust/pollen) - Qty: 1
• Cabin air filter (activated carbon/charcoal) (if equipped) - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and open the passenger door for more space.
• Slide the passenger seat all the way back and remove the passenger floor mat.
• Have your flashlight ready—most of the work is under the glovebox.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the passenger under-dash panel

• Use a flashlight to locate the under-glovebox trim panel (the panel above the passenger’s feet).
• Remove the fasteners using a Torx T20 screwdriver.
• If the panel is clipped in, gently release clips using a trim removal tool (plastic). Pull straight down to avoid breaking tabs.
• If a small footwell light is attached, gently unplug it using a small flat-blade screwdriver (press the locking tab, then pull the connector out).

Step 2: Locate the cabin filter housing

• With the panel removed, use the flashlight to find the cabin filter cover (a rectangular cover on the HVAC box area under/behind the glovebox).
• Clear loose dust with a shop vacuum with crevice tool so debris doesn’t fall into the housing.

Step 3: Open the filter cover

• Release the cover clips and/or remove small screws using a Torx T20 screwdriver (some versions are clip-only).
• Lower/remove the cover carefully; use nitrile gloves because filters can be dirty.
• Take a quick photo before removal.

Step 4: Remove the old cabin filter(s)

• Pull the filter element(s) straight out by hand while supporting the housing edge.
• Note the airflow direction arrow on the filter frame (usually labeled “AIR FLOW”).
• Use the shop vacuum with crevice tool to gently clean the inside of the housing (do not damage any foam seals).

Step 5: Install the new cabin filter(s)

• Insert the new filter element(s) in the same orientation as the old one(s).
• Make sure the airflow arrow matches the vehicle’s airflow direction (match what you observed on removal).
• Check that the filter sits fully flat and the seal edges aren’t folded. A pinched seal can whistle.

Step 6: Reinstall the filter cover

• Reinstall the cover and engage all clips.
• If screws were removed, reinstall them using a Torx T20 screwdriver.
• Note: Mercedes typically does not publish a torque spec for these small trim/cover fasteners—tighten snug only (do not overtighten).

Step 7: Reinstall the under-dash panel

• Reconnect the footwell light (if equipped) by pushing the connector in until it clicks.
• Position the panel and press clips into place by hand.
• Reinstall fasteners using a Torx T20 screwdriver.

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✅ After Repair

• Start the vehicle and run the blower fan from low to high to confirm strong airflow.
• Switch between fresh air and recirculation to verify no unusual noises (whistle/rattle).
• If you notice a musty smell, run A/C for a few minutes, then turn A/C OFF and leave fan on for 2 minutes to dry the evaporator.

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💰 DIY vs Shop Cost

Shop Cost: $120-$220 (parts + labor)

DIY Cost: $20-$60 (parts only)

You Save: $60-$200 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.0 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.