I dont have an owners manual and I'm trying to find the location of the fuse for the fog lights in the fuse box... Which number is it??

depends on the make, model & year of the vehicle.

If it didn't come with fog lights, it may also have not included a fog light relay and/or fuse. Check the owner's manual for fuse and relay locations, and then check if the necessary parts are there.

Have you tried looking in your Owner's Manual? Many modern vehicles only give fuse numbers on the fuse boxes. The chart to see what these fuses go to are usually in the Owner's Manual.

Please note that there are 2 different models of a 2009 Mercedes C300. There is a C300 4MATIC(204.081) V6-3.0L (272.948), and a C 300 (204.054) V6-3.0L (272.947).

There are also 3 different fuse boxes in your vehicle. It would be helpful to know what it is you are looking for so the fuse location can be looked up.

Please also review this article:
Where's The Fuse?

the key must be on and the headlight need to be on low beam for them to operate,your dash button for the fog lights should have a small light in the switch when you have all the above on,if there is no light in the switch,check your owners manual in the glove box,it will show you fuse box locations and what each fuse feeds

Consult your Car Owner manual to locate where the Fuse Box is located: Check the appropriate fuse(s) for the appliances in your car that are not working - I suspect that the AirCon, RearWiper and Fog lights are sharing the same fuse as it would be extremely unusual to have 3 separates fuses blown at the same time. ps. The Polo usually has some spare fuses in/near the Fuse Box.

According to another post, You can find the #35 fog lamp relay inside the main fuse box, which is on the passenger side of the engine compartment under the hood. The relay is clearly marked on a diagram on the inside cover of the main fuse box.

http://www.tmar.net/fog_lights.htm

I recommend you check the fog lamp relay. I believe it's located in the engine compartment inside a plastic box with a removable lid. Please check your owner's manual for the exact location.

FYI, here's a link to a Mitsubishi Eclipse fog lamp relay at RockAuto parts. Page down till you get to the details. It cost ~18$
http://www.rockauto.com/catalog/raframecatalog.php?carcode=1398955&parttype=3717&a=FRc1398955k1481568

reference your owners manual for relay location, if you do not have one you can download it at www.fleet.ford.com , the relay for the fog lights should be under hood in power distribution box, ford relay are notorious for hanging up in closed and open positions, pull the relay and see if the lights go out? if so replace relay, try the same for interior lights, that relay should be inside in the fuse box. hope this helps, let me know

First need to test for power at a fog light. If no power, then I would check fuses. there will be a fuse box under hood and one under the dash. Take a test light and test all fuses on both sides of each fuse. Could be called running lights, aux lights, driving lights, etc. Any fuse that does not have power on both sides is suspect. Note: the headlight fuses cannot be checked unless the headlights are turned on. the owners manual will also tell you the location of the fuse box and which fuse in the box to test. Could also have a relay that has failed , it will be in the underhood fuse box.

The 15 amp FOG fuse is in the fuse box in the engine compartment, at the bottom, right between the fog light relay and the fan #1 relay. The fuse is by itself, there are no other fuses next to it. Hope this helps, and thanks for choosing FixYa.