The malfunction light has come on . my chevrolet lacetti is under warranty. what happens as regards to paying for repairs if it is needed

TAHE SERVICE AND REPAIR MANUAL WITH DIAGRAM WILL PROVIDE YOU STEP BY STEP HELP TO LOCATE AND FIX THE PROBLEM EASILY AND YOU WILL GET THE MANUAL FROM THE GIVEN LINK https://toolsnyou.com

There are no rear fog lights, they only put them in the front.

I have no idea what a Lacetti is, but if you suspect a fuse problem, why not just check them all?

check with GM spares as the sensor is probably the same used in a wide variety of Chevs of the same engine family.

Visit the on-line store, known as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.

we need the trouble codes, please.

Please see my tip at http://www.fixya.com/cars/r5932051-check_engine_light_check. These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

The check engine light comes only when the computer control unit (called the PCM) senses a fault in the electronic controls of the engine and/or the emission system, there are about 200 possible faults that turn the light on, to know what has developed a problem you must have the system tested, this is called an OBD2 fault code test

Pretty common problem with these. Here's a guide to learn how to fix GM instrument clusters yourself, I used it to fix mine and it worked great. How to guide for Silverado instrument cluster repair
How to guide for Silverado instrument cluster repair

u will need to replace the brake light switch, it is located at the top of the arm the brake pedal is attached to, simple hand tools to replace, very easy job, part very cheap.

It may be the same problem as my 56 plate Lacetti. The yellow malfunction light came on two weeks ago and two days ago, both times shortly after filling up with petrol to the brim, and I suspect it is the petrol sensor as I only clicked the petrol cap once after fitting it back - the handbook says click it several times. The yellow light also came on yesterday after taking the car a short journey so it is likely that the sensor is still picking up a small escape of petrol, but the car has been fine today with no light appearing now that the fuel level has dropped a bit. Like you, I have not noticed any drop in power with the light on.