Common problem?

Hi, I've been reading this forum for a while but this is my first post. I've owned a 2.0 S60 TS for 10 month now and love the car. Over the past 3 month the idle speed has been "unstable" It seems to go up and down from 500RPM to 1500RPM when the engine is warm. It still starts every time and once some revs are applied it drives perfect. There are no warning lights on and I've had the car connected to a diagnostic machine and nothing shows up. I took the car to a garage today but it needs to go back next week as they couldn't find anything obvious so need to spend some time on it. I've been reading about the ETM issues on this forum...does this sound like it? does Volvo need to reprogram something? Or is it more likely to be a mechanical failure of some sort that a more local and cheaper garage could sort? If i take it to Volvo can i get them to sort it for free if its a known fault? Thanks very much for any help Lee UK

What year is the car?

sorry forgot about that....its 2001 Lee

Hi Take it to the dealers you have it serviced with they should do it for free . If you dont have it serviced at the main dealer I would personally start too to build up a good raport with the service manager . You may feel like you are paying a bit more to have it looked after but if it is a pre 02 it will probably pay in the end and if their anything like my dealer was before I got feed up with the car and sold it they were fantastic , rather frustrated they coulnt help more alot of the time as they were aware of all the problems but wernt allowed to do more obviously as govened by higher up . A big smile and tell them that it cut out on the motorway and nearly killed you , thought volvos were safe . Youl probably find they cant do enough for you . Good luck