Hi can anyone help I have an Audi A6 avant 2.0 tdi the oil earning light came on so I checked the onboard computer it said it was half full so I put a litre of oil in now I’m worried that I may have put too much oil in 

Leave the engine off for 10 minutes, then check the dipstick (by taking it out, wiping it and then dipping it back in and pulling it out to check) - this will tell you what your oil level is.

Hello Andrew,

Thanks for joining and posting you plea. 
When you say the oil warning light came on, and you talking oil level warning light, or oil pressure warning light?

If it was indeed the oil level light, and you put 1 ltr in from half full, then I wouldn’t expect it to now be overfilled. 
Does it have a dip stick?? - possibly not if it has an electronic level display. 
Anyway - as Mike says if it has a dip stick, but I would check first thing in the morning before starting the engine - car on level ground. 
If no stick - same procedure but check the electronic displayed level before starting after its been standing overnight. 
Apologies for being direct, but are you from the school of total reliance and faith by acting at a point where a warning light appears, rather than regularly checking the level of a morning? 
Kind regards,

Gareth.