You will find the Horn under the Drivers side, it's access for ease is under the body ( Just done our 206 It's similar) the horn on these cars are rubbish / cheap, I have tried the obvious, contacts, the horn is open to the Weather, if you look on ebay, they are a Fiver, that tells you everything, the Horn Connector is a 2 pin Clamp, press each side of the clamp to release, I exchanged for the one's I had spare for my Beema but had to replace the connector ( Not a bad job to do) easy way to do the job, "Safety in Mind" Jack up the car, remove the Offside wheel / Inner Splash Lining About 6 Plastic Plugs + one Torx Srew on the lower Left hand side as you look at the wheel, as soon as you lower the inner lining you will see the horn, if you open the bonnet & look to the lower left of the Radiator, you will see it.