hi im new to the forum and was wondering if anyone could answer my question my friend has an audi a3 2.0tdi its a 2005 model 55 plate the oil level light came on the dash so he checked the oil and topped it up 1 litre the oil is at the correct level on the dipstick but the light is still on he was told it may be a faulty bonnet switch?, also the abs warning light came on is there any way of eliminating which sensor it could be as he does not want to stick it into the audi dealer for diagnosis as they charge a fortune any replies would be grately appreciated cheers mick