Hello,

I have a 2004 s40 2.4i (current model). The car has very low mileage and recently went to the local Volvo dealer (who will remain nameless to protect the guilty) for a major service. The mechanic who replaced the oil neglected to refit the oil filler cap (left it in a hollow ear the radiator) and I drove the car for three days after which the "fault in the emissions system" light came on and stays on. When I lifted the hood I saw that oil has splashed around the oil filler hole that should have been covered by the cap. I saw the oil cap sitting near the radiator in a hollow. To anyone out there who may know - could the fact that the oil chamber has been unsealed while the car has run for 30-odd miles lead to the "fault in emissions system" light being triggered, and if yes, will the car's computer reset the warning light? The engine runs well, and fuel economy seems normal. Thanks.

 

Probably the same as leaving the fuel tank cap off and getting the CEL. I would clean up the engine, replace the cap and the lost oil, then have the codes erased (can be done at any parts store with an OBD-II reader like Advance or Autozone). Then drive the car and see if the light returns.