I have a 2002 Honda Civic with about 100K km on it, lately it seems when I'm at a stop light it has a loud idiling sound with ticking, but it doesn't seem to happen all the time. Any ideas?

Have you run it low on oil ?

Valves may need adjusting. Also, I recommend that you use full synthethic engine oil; e.g. Mobil 1. Change synthetic oil and filter every 6 months or 9,600 km, whichever comes first.

Oil levels are good and was changed only 4000km ago, but that is probably over 6 months ago.

Thanks

Oil levels may be good but that doesn't mean they changed the oil last check up, only added oil. Sticky valves can be caused by dirty oil. Don't forget the heat transfer from an engine makes the old oil really thick and gucky. So mayb e get a complete oil change and a complete engine check. I have that done on a regular basis on my Subaru every 3 or 4 months.

Turns out it was a heat shield over the catalytic converter that had rusted out and was hanging and making a noise. It was removed and now there is no more noise!