I drove the car through 1-2 foot of water yesterday. The car made it through but juddered a little. Since then I have had a loss of power (like limp mode), but i have no warning lights on the dash. I have checked the oil for contamination and was fine, I have checked the air filter which did have some water in the tray. The car starts ok and ticks over fine and there is no abnormal noises etc. It drives ok apart from the lack of power which notices more going up hill and only doing 70mph on the motorway with foot flat on the floor. What could be the problem?

Brett, August 2013

Disconnect intercooler hoses,if water pours out from there then you can maybe expect engine damage,head off job and a huge bill.
Always avoid going through water,no matter how deep.

cdc, August 2013

If not already done: Drain any water in the filter's tray and anywhere else it may have accumulated.

Apparently, your air filter got wet with dirty water.
That water probably deposited dirt and other contaminents into the air filter, clogging it. You probably need to replace the air filter.

Electro, August 2013