Engine air filter replacement

Introduction

Applicable to all engines (H4D and H4Bt).

Replace every: 20,000km or year. It should be replaced earlier if driving in dusty environments.

A clogged engine air filter may impact fuel economy: it will create more resistance and therefore, increase the pumping losses.

Note: recommendations are given according to the French RTA's (Revue Technique Automobile) maintenance plan, matching Smart 453's maintenance plan in this case.

What you need

Step 1 Accessing the engine hood

Engine air filter replacement, Accessing the engine hood: step 1, image 1 of 1

Open the trunk.
Remove the trunk carpets.

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Step 2 Acessing the engine compartment

Engine air filter replacement, Acessing the engine compartment: step 2, image 1 of 1

Unscrew the 6 T50 screws by hand or using a wrench and a socket.
Lift and set aside the engine hood.

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Step 3 Disassembling the airbox

Engine air filter replacement, Disassembling the airbox: step 3, image 1 of 2

Engine air filter replacement, Disassembling the airbox: step 3, image 2 of 2

Unscrew the 2 Torx T25 screws.
Disglog the air filter lig by slightly pushing/pulling it forward then lifting it.

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Step 4 Replacing the air filter

Extract the used air filter.
Dust off the air box from any debris residing in it.
Optionnal but recommended: proceeed to a throttle body, MAP sensor and air manifold thermometer cleaning (see other tutorials).
Install the new air filter.