I've been having a problem with fumes getting inside my Focus. They are even more obvious if I open the bonnet and take a good sniff - they appear to originate in the engine area. They're getting inside via the vents.

My mechanic inspected the exhaust, fuel injector seals and much else. He came to the conclusion that the issue was caused by two things: the fact that the EGR valve was stuck open plus the need for a DPF regen. So the EGR valve has now been changed and the fumes do seem a little reduced. But there's still a kind of smoky, sooty smell getting inside.

There's something I don't understand here: Whatever is going on with the DPF and EGR, I would have assumed that all gases would nevertheless remain 'contained' until they exited the exhaust at the back. Everything's sealed, right? In other words, I don't see how fumes can be in the engine area unless there is also some sort of leak somewhere. Or am I missing something basic here?

So any explanations would be welcome. Can the issues with DPF and EGR on their own lead to fumes in engine area?

Or is the mechanic on the wrong track?!

AND... is having an artificial regen on the DPF likely to help the sooty fumes issue?

Thanks!

Edited by Bernie Smith on 16/11/2017 at 20:14