Are you sure its the 'service' light and not the 'check engine' warning light? Hopefully someone else with a gen-2 car can confirm whether or not this is the case. If it is an engine check light, then you should be able to use your scanner to determine what the fault (code) is.
My cars's lambda fault causes the engine check light to illuminate the next time the car is started (after a short time), possibly (and I'm hoping this is the case) with the exception in colder weather (for some reason), as it did over last winter, which is handy as it gets service / MOTed around Christmas/New Year.
If your issue is a fault code, then its well worth checking to see what it is, in case the problem is significant or ptentially terminal if not resolved. According to a local indie mechanic, mine shoudl not prove too much of an issue from a longevity pov but will be expensive to fix, as removing the sensor could well strip the threads of the hosuign, necessitating a replacement CAT as well as the sensor, costing £1500 for the job, more than the car is worth.
