I have recently bought a 523i. It runs really well, but on cold starts it has a very strong smell of fuel coming from the exhaust. I have been thinking if it could be a leaky injector or two? If that's the case, how do I confirm it? Also would it be enough to try cleaning them using some fuel additive or is it more likely the o-rings or maybe the entire injectors? Also would you then replace all of them?

PS. my engine is an N52B25

 

What is your year and model? Personally with a 98 feedback and no warranty I would find them somewhere else like FCPeuro

 

It's a 2006