Definitely NOT a mechanic here, so not sure I'll be of much help but noticed this question was still unanswered....
It probably depends on where the leak is exactly. For example, I had a horrible gas leak that was discovered by the guy changing my oil a couple of weeks ago- turns out my Fuel Filter needed replaced as it had a crack in it.
I just did it on 2003 buick rendezvous,i bought a can of fix leak,oil,freon all in one from advance and hooked it up to the lower a/c port and charged it to about 35 psi and the air blows like new.
depends where the leak is, and how bad it is.
How to fix this depends on where specifically it is leaking from.
Figure out what tripped the code and fix the problem
antifreeze leaking into the oil pan
yes
If you have an engine oil leak on your 2002 Peugeot 206 1.4, you can use an oil stop-leak product to fix it.
Replace defective part
Replace the seal.
it needs fluid and you need to find the leak and fix it
Un plug the drain which is on the firewall behind the right front tire.
You don't, fix the vacuum leak that's causing the eratic idle conditions