How to Reset a Mercedes Service Warning Light

1. Insert the key into the ignition. Turn the ignition switch to ON but do not start the engine.
2. Press the up or down arrow button on the left side of the steering wheel until Service Interval Reset is displayed on the instrument panel.
3. Press and hold the R/Reset button on the instrument panel for at least three seconds until the service warning light resets on the display.

How to Reset the E90 Cabin Air Filter Warning

1. Replace the cabin air filter if you have not done so already. Open the hood and examine the passenger side of the engine bay near the firewall to find the cabin air filter housing. The filter extends from one end of the engine bay to the other.
2. Remove the six 8mm bolts from around the cabin air filter housing. Lift the cover off to expose the filter.
3. Remove the old filter and discard it. Insert the new filter, replace the cover and tighten the bolts.
4. Insert your smart key into the electronic ignition. Press the Engine Start/Stop button without placing your foot on the brake (or on the clutch, if its a manual transmission). Wait for the service warning light to disappear.
5. Press and hold the trip odometer reset button (on instrument panel). Wait for the oil can icon to appear (it will appear after the service triangle) to indicate you are at the service menu.
6. Toggle the indicator stalk until you reach Cabin Filter. Press and hold the BC button at the end of the stalk to reset the interval and turn off the warning display.