For some times now, I have been battling with water ingressions in to my car’s cabin(interior). It was not funny at all. Sometimes, when it rains, or I get to wash the car, the rear back seats floor usually gets ponded with water. This has caused a whole lot of mold growth in the interior, stains on the aprons, and foul odour as a result. According to some body shops I have visited, almost all of them advised that the sunroof of the car be permanently sealed, and the boot grommets be replaced. I was not certain about their diagnosis, and decided to get to the root cause of the problem, and perhaps, have it fixed.


Some of the signs to watch out for are;

  1. Wetness on the floor of the car, or the seats. This could lead to drivability malfunctions, because of wire harnesses might short out during the operations of any electrical/electronic circuit that have been routed under the floor.
  2. Mold growth. This translates into the greenish or grayish formations you see on areas or portions of the interior, such as on dampened leather seats, or aprons and carpet/ rugs.
  3. Foul odors. Have you ever perceived the odor that comes from a flooded vehicle? Sometimes, as a result of wetness, the odor can be unbearable. These Odors are formed from bacterial actions on these molds for growth. Bacteria strive well, in the presence of air and water.
  4. Discolorations on any of the cabin/interior aprons, especially those that are positioned at the rear, front and side airbag positions.
  5. Rear light bulbs often gets replaced, because of the presence of water accumulations in the enclosures, causing short circuit problems.


Majority of these problems are caused by, (a) ruptured or clogged sunroof drain hoses and appurtenances; (b) clogged fuel filler drain hose or port; (c) bad grommets, which can be found on windshield/windscreen or rear lamp casings; (d) corroded floor pans, either from years of under-body water intrusions, which could be from erosive flood waters; (e) missing or bad under-body/floor seals, and (f) misalignment of body parts such as doors trims, etc., from a body shop.


  1. The first thing in fixing issue like this, is to identify the source of the water/moisture intrusions. Where is it coming from? Lookout for signs of discolorations on the aprons of the rear and front of the airbag locations, and also the various grommets of the vehicle. Are the various seals intact?
  2. To be able to identify this, you got to have an idea about the sunroof plumbing of your specific vehicle. Some vehicles have sunroof drain hoses extended all the way from the front, and to the rear of the vehicle.  Having a basic knowledge on the plumbing, helps you determine exactly where the water could be coming from, and what component to inspect.
  3. If you have never had any major body shop repairs done on your car, and all other things checked out great, including the door and rear headlights grommets, your first point of call should be clogged sunroof drain hose(s) and appurtenances.  
  4. Usually, some of these blockages are as a result of degraded organic matter, such as leaves, bird droppings, and sometimes, dusts/grits.
  5. If you are a DIYer, you could remove, and unclogged the sunroof hoses, and appurtenances, by applying compressed air through them, or using warm water and a small garden hose to help dislodge the particles in the plumbing.
  6. Replace or repair all or some of the leaks from the windscreens/windshield, and the underbody drain seals.
  7. If it is always possible, reduce the rate of parking your vehicle close to a vegetation. Remember, it is these organic materials from this vegetation that degrades and clogs sunroof drain hoses when they eventually fall on the car.
  8. . Use car covers to protect from fallen vegetation or debris from the environment.


It is sometimes a daunting task to pin down the source of water intrusions in a car’s interior. Solving the problems once and for all, keeps your vehicle in top shape (aesthetic wise), and prevents intermittent drivability/performance problems that may occur (some wire harnesses located on water prone locations such as the under-bodies, and sunroof drain hoses).

A stitch in time, saves…


Vehicle type: 2004 Infiniti M45

Engine type: VK45DE

Engine capacity: 4.5L V8

Transmission system: Automatic


Water gets ponded at the rear seats floor, the jack positions in the boot filled with water, and discolorations on the side airbag aprons.

Rear seat floor wet with water
Water stains on side airbag
Removed cover on the side airbag location passenger side


  1. Identifying where the water was coming from, took me sometime. Had to trace the water marks or paths on the discoloured side airbag aprons to realize the intrusions was from clogged sunroof drain hoses and appurtenances.
Side passenger side airbag cover removed, while tracing the sunroof drain hose

Rear passenger side nitrogen gas can as part of the airbag system. Do not disconnect.
Sunroof drain hoses

2. Unhooked the two sunroof drain hoses, and appurtenances, and discovered they were all clogged. Using a piece of copper wire, did the magic, by inserting it into the hoses several times, and flushing through with warm water, using a garden hose, until clear water came out of the outlet of the hoses. Fuel tank filler drain hose and port was also blocked, which if not taken care of, would contaminate the petrol in the tank, thereby causing driveability issue s, and corrosion to fuel pump.

3. Reassembled everything back, and poured a bucket of water over the sunroof, in order to test for leaks. No leaks or water intrusions was observed after the fix.

Drain sunroof hoses
The junction like appurtenance that attaches to the sunroof, and filler tank drain hoses. It must be thoroughly washed to removed all forms of dirt. Compressed air could be used, if you have one.
Showing the hoses
Fuel filler drain is also blocked with grit
Using a copper wire of same diameter with block exit to clean off the grit
Using some quantity of water to flush through the hole
Same procedure
Looking at the front drain outlets here, they were filled with decayed matter, and grit. This prevents proper water discharges
Picture of the sunroof. It had no leaks around its seals.
This is the sunroof discharge outlet, underneath the rear of the car. There are other ports at the front of the car.

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