I apologise if this has been asked and answered.
My wife's 07 XC90 typically lives in the garage, but lately she's been parking it in our driveway as she hates parking next to my truck project in the garage. So the driveway is a significant hill and her car when it rains floods in the front if facing downhill, and rear floorboards if facing uphill. Well today it was facing downhill, and all of the sudden after a heavy rainfall there was a puddle on the driver's side floor. I noticed water behind the obd-ii cover as well.
I managed to get the lights off right side parking lights. But when I moved the car to level ground I had 5 different warning messages. Is it possible that the ECM on the driver's side has water in it? And could the sunroof drains be the culprit?

 

That is a good question. Have your mechanic check all over for leaks. Sounds like you may need some rubber trim around your car. Also especially check the sunroof.

 

When I get a chance I'll pull the drip tubes from the door pillars and see if they are still intact.

 

On some xc90s the CEM was prone to water intrusion due to drainage issues under the cowl. Leaky sunroof drains are common also. You should pull up the door sill to expose the edge of the carpet and try to get your hand underneath the front carpet/s - there is up to 4 inches of foam padding glued to the bottom of the carpet. It gets really nasty/moldy/stinky if you don't dry the carpets out - The rears get soaked also sometimes. Unfortunately the best way to do that is to remove the carpets, and on the drivers side the distance to the gas pedal and brake pedal is increased making it almost impossible to drive the car safely with the carpets out. It takes a minimum of several days for the carpets to dry.

 

Hoonk, I've recently read that the drain tubes and cowlings are prone to leaking. The oddity of this is it only seeps inside the car on a hill, if it's on level ground no water. That's what is really making me scratch my head.

 

At an angle more water from the roof or hood would be directed at the cowl area, when parked flat the water drains off all directions on the hood, front and rear on the roof.

 

Seems to be the my problem, the crappy part is my driveway is a hill, so I guess when it's nice out again I'll have to tear into it and find out what is causing it to pool in the floor boards. Nose up it's the rear floorboards, back end up it's the front floorboards that pool up. I can't win for losing.

 

Then you are going to have several inches of water under all the carpets. In some cars you can hear it sloshing around when driving! Sometimes the amplifier mounted in the passenger floor board gets water damaged, in cars that have them.