01 2.0hdi Gear selection problems - Craig2008
My car is a Peugeot 406 2.0hdi 110bhp.

At the weekend I drove through a number of floods faster than I should have, and I now struggle to select gears.

Randomly, when I select gears, it feels as if the gear stick wont push fully into the gear I want. Usually, after 2 or 3 attempts, the gear will fully select.

Does anyone know what this might be?
01 2.0hdi Gear selection problems - RichardW
You've probably filled the gearbox up with water. Get the oil in it changed pronto before it does some lasting damage!
01 2.0hdi Gear selection problems - 659FBE
I did exactly the same thing in a 106. The gearbox becomes unbelievably obstructive and an oil change is the instant cure. Get the oil out asap and refill with the correct grade.

It happened at about 12k miles - the car has now done 140k without any gearbox problems, so no long term damage.

659.
01 2.0hdi Gear selection problems - Bromptonaut
If, like it's near relative the Xantia, this car has a cable operated change I'd get the cables looked at. Mine rusted after a period of inactivity but I guess driving fast through floods could mean some debris being picked up.

Not cheap to resolve as there's quite a bit of dismantling involved in accessing/changing the cables.