white/grey smoke out of exhaust when reving my car

white/grey smoke comes out of my exhaust when i rev the engine but not when i firststart the engine with out reving. It also just failed its emissions test if any one has any ideas why this has happened let us know, cheers

white/grey smoke comes out of my exhaust when i rev the engine but not when i firststart the engine with out reving. It also just failed its emissions test if any one has any ideas why this has happened let us know, cheers

Post the emissions results , that may give a clue. Also is it petrol or Diesel? , and is it Peugeot?

Tell you what.

Tell us what car it is.

Petrol or diesel?

How old?

How many miles?

Then there's a chance we could suggest something!

First guess. It's a Prius and the battery pack is crystallised causing a massive short when it first starts up and the smoke is the crystals vaporising so it works properly again.