Anti Pollution Fault following puddle

I have a 406 2l hid 110 estate 02 plate.

Last week I drove through a big puddle and got immediate loss of power followed by anti pollution fault and limp home mode. Some water in engine bay esp left side but air filter dry. Rac and garage diagnosed EGR valve fault (lots of diesel smoke from exhaust when revved). Car went to garage the Wednesday night and had new EGR valve fitted the Monday. So in a dry garage for 4 days. All cats cleared. So assumed the puddle was coincidence.

However 1 week later I got the exact same fault after driving through a s similar puddle. Loss of power and limp home mode.

So I think the previous fault was water related sensor fault plus faulty egr valve, but the sensor dried out over the 4 days in the garage.

Now it seems every deep puddle is going to cause limp home mode.

Does anyone have any idea where to start checking sensors? There isn't much water in the engine bay but there is some, mostly on the near side near the bottom of the turbo intercooler. And the bottom of the car is clearly wet from going through the big puddle.

Or any other ideas?

Grateful for any advice!

 

Update to post:

Anti Pollution Fault warning now cleared. Car is driving better but very little to nil turbo boost whilst driving. Particularly at low speed, with no sudden kick at higher revs either. However when stationary I can hear the turbo whine and air hiss and see the hoses bulging. Yet no actual turbo boost under load.

Recently fitted a new Maf and egr valve, plus just tried driving with the maf unplugged with no improvement.

Therefore any ideas why the car would loose turbo due to driving through a puddle?

She's a 2L HDI with 164k miles, and I don't want to give up on her yet!

 

OK so I just got the car back from the garage. All that was wrong was a missing clip on the throttle cable, which meant pressing the peddle didn't do much. I guess the puddle caused a sensor fault that displayed the anti pollution fault and put the car in limp home mode. Then it dried out and the fault cleared, but me fiddling in the engine bay knocked the clip off, delivering the on going fault. ( and garage refused to charge me for the second repair, how nice is that?)

Garage has hooked up the lowest hanging sensor (talks between the fuel pump and common rail I think) so it less likely to get wet again.

I'm going to seal the sensor in a plastic bag plus seal another blank terminal in case water ingress was the problem, then seal up an opening in the under tray that a bow wave prob gets through (but leave some drainage holes). That should stop future water based probs.

So that's what I think. Water on sensor leading to other problems elsewhere. Hopefully fixed now! Hope this story helps someone else!