T5 smoking on tickover

[craigE]

After getting caught up in some really slow moving traffic recently(coming off an airbase after an airshow)my car started to smoke very badly on tickover.I was stuck for about an hour and a half and during it's fit of smoking the lambda light came on on the dash, once we got moving and back on the freeway the smoking stopped but the light stayed on , it got me home ok and once I had it checked over at my local garage they said nothing was wrong with the car and just shut the light off again through the diagnostics.What bothers me is he said that this sort of behaviour is normal when stuck in traffic for long periods, is he right or is there a fault somewhere?. Any ideas please.