But the
electrics is standard and will always generate an error if the resistance of the tungsten wire in the bulb installed will be smaller than the one that should have been installed.
Tungsten wire bulbs transform much of the electric energy into heat. And only a part into light (the internet says around 5%). I don't know if we can assume that a 10W bulb will generate twice as much heat as the 5W bulb, but it will be close to it.
You have several choices:
- install a LED instead of a tungsten wire bulb. I think that your Punto has CAN, so you'll need a LED that will not generate the same type of the error (safe for CAN, or different depending on how the producer calls it). I don't know how it is concerned in the UK, but generally the lamp is homologated (= road legal) in its entirety (= lamp + light source). If you change one of these, the homologation is void. In fact that could also be the case with your aftermarket lamps. No idea if they have a homologation. It shall be marked on the lamp. Some producers (especially from China) put homologation marks without having the homologation done;
- use a 5W bulb, in theory safe for the lamp, but less visible. To avoid the error, you should add a specific resistor (the best I think would be on the side light wire just before the lamp). To calculate the right value you should check the resistance of the 10W bulb, substract from it the resistance of the 5W bulb. That will fool the CAN system in the car but should do nothing to the bulb / light. Resistors generate heat, too;
- use a standard bulb as per manual (10W) and hope that it won't burn the plastic of the lamp;
- revert to the original light
