When ive had it in the past ive just taken them all out nad put them back in and its been fine, but to quote edde:
"There is a common problem with Clios with the the SERV and AIRBAG lights come on it usually happened in the first few month but older cars out of the 3 yr warently have had the problem. Its due to the fact that the wires under the seat don't make a good conection and they can give a reading of a resitance over 4 Ohms when they do this it causes the warning light to come on. A simple short term fix is to fiddle with the wires under the seat and the problem will go away.
On the early cars the solution is to look under each of the seats. You will see a grey connector.
On the passenger side disconnect it and cut the Blue and Brown wires off both sides. Then solder the Blue wire to blue, and the Brown to the other brown. Make sure you use insulating sleeves over the soldered connections..
Under the driver seat there are two pairs of wires in the grey connector. Only cut the Blue and Brown wires and solder them together as above. Then reconnect the connector.
On the facelift cars it is ONLY the passenger side connector that is affected.. So again cut and solder the Blue and brown wires.
There is a Renault technical note out though and it will be done under warently if you car is affected."