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Servicing guides and mods

Changing Interior Bulbs

Modification Details

This page now covers the Roadster, old fortwo 450 and the new fortwo 451.


Lever the side of the bulb diffuser down.

Slide the unit to the left.

Squeeze the two plastic clips shown below.

Slide the bulb and its holder to the right.

You can now pull the bulb out and replace with another 501 style bulb or LED.



To remove the light put a knife under each side of the lip and lever forwards.

Once out the bulb can easily be seen (circled in red), replace with a 509T style bulb or LED.

Make sure the bulb or LED works, if not, remove and turn 180 degrees before refitting.
When it's all working simply clip back into the console.


Insert a flat screwdriver into the front edge and lever open, the whole lens will fall away.

Lever the 2 white clips (circled) inwards, this will come away to reveal the connection.

The holder accepts 36mm to 39mm festoon style lamps and LEDs.

Speedo Bulbs

Firstly you need to equip yourself with the correct tool.
You will either need a T10 torx bit or a 1.5mm allen key, they have to be quite long.

You will also need the twist fit socket (found on the rear of the speedo),
11/32 socket or a set of long nose pliers and some replacement bulbs.

Use either your T10 bit (T10 screwdriver) or 2mm allen key in these holes (circled)
and on the same 2 on the other side. The screws are quite far in.

Put your fingers right on the edge as pictured and pull slightly towards you to free the housing, do this the other side too. The whole housing containing the speedo will now be loose, lift it and turn it clockwise and rest it on the dash.

It is not recommended that you disconnect any wires to aid fitment unless you have to.
The reason for this is that some speedos can revert back to showing kilometers.

Disconnecting the RPM gauge (circled red) can sometimes cause it to be inaccurate
but it can be fixed by looking 
here. Disconnecting the other cable (circled green) can sometimes cause the odometer to revert to kilometres, smart can fix this.

Bulbs numbered 13 and 14 are for the speedo. Bulbs numbered 15 and 16 are for the LCD.
These are best removed with the supplied remover.
Look to the right of bulb 13 and you will find a plastic tool attached to the back
of the speedo, twist it off. This fits the 509T bulbs perfectly.

Twist them a quarter of a turn anticlockwise and pull the bulb out.

Using the 11/32 socket  or the long nose pliers, insert and twist a quarter turn
clockwise. Once they are all fitted check the lights, any that don't light will
need removing and rotating 180 degrees before refitting. When all the lights work
(you may need to fiddle with them a bit) reassemble the speedo pod.

Dash Pods

Firstly remove the coloured outer ring, they clip straight on and come off easily.

Place a thin headed screwdriver next to 1 and 6 on the tacho (3 and 9 on the clock) 
and lever to unclip the 2 clips (circled in red).

Lever the hands off with a strong fork

Place the knife down the side of the dial and slowly lever both sides.

Going from side to side the dial and backing will slowly come up and come out.
If you have aftermarket dial faces they can be fitted now, to fit the speedo dial, look 

With the dial out of the way, carefully unclip the ribbon connector from the circuit board.
Using your thumb, bend back 1 clip at a time (circled in red) and pull the PCB forwards.

Circled in red is the 509T twist fit bulb that you can change, these also take 
the standard twist fit bulbs used in the speedo console.

Fortwo 451

Lever the interior light unit on one side.

The light unit will now swing down.

Remove the bulb by pushing it to one side and lift the other end out.

Refitting is the reverse of above.

The holder accepts 36mm to 39mm festoon style lamps and LEDs.

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