Debris accumulation in the moonroof drainage channels leads to water intrusion into the cabin, potentially damaging electrical systems and causing mold.
Reviewed by SubaruReview Editorial Team · Last reviewed 2026-05-15 · Editorial standards
This is one of several documented Forester problems we track, and it fits inside the broader Reliability & Common Problems guide. If you're weighing repair against replacement, cross-check the Subaru repair-cost database and any open NHTSA recalls on your VIN before booking a shop.
When the sunroof drain tubes become restricted by debris or disconnect from the assembly, rainwater overflows the internal gutters. This water travels behind the interior trim, soaking the headliner and pooling under the floor carpets. Prolonged exposure can short out the Body Integrated Unit (BIU) or wiring harnesses located in the kick panels.
Tapered rubber 'clamshell' exit valves at the bottom of the drain tubes trap silt and organic debris, causing water to back up the pillar. Over time, heat can also cause the vinyl tubing to shrink and pull away from the sunroof tray nipples.
Tapered rubber 'clamshell' exit valves at the bottom of the drain tubes trap silt and organic debris, causing water to back up the pillar. Over time, heat can also cause the vinyl tubing to shrink and pull away from the sunroof tray nipples.
National average $150–$1,200. $150-$250 for a professional cleaning and clearing. Up to $1,200 if the headliner must be dropped to replace disconnected tubes or if interior carpets require professional mold remediation and electrical cleaning.
Difficulty 3/5. Clear the blockage using a flexible cable or low-pressure air. If the drain tube has detached or shrunk, replace the drain tube with updated Subaru part numbers and secure with hose clamps. Re-seat the rubber grommet at the exit point in the wheel well.
Wet floor carpets (typically driver or passenger footwell); Water dripping from the overhead console or A-pillar trim; Musty, mildew-like odor inside the cabin; Excessive window fogging on the interior; Sloshing sounds coming from the dashboard or pillars during turns
Owners typically pay $150–$1,200 at an independent Subaru shop, parts and labor included. Our Subaru AC Compressor Replacement Cost guide breaks the job down by parts, labor hours, and where the money actually goes.
We rate it 3/5 on our DIY scale. Confident wrenchers can tackle it in a weekend using the permanent-fix steps above. Cross-reference the reliability & common problems hub for related jobs worth bundling while you're in there.
Dig into the Problems Database to plan your next maintenance sprint, or browse every model hub for buyer's guides, generation breakdowns, and known-issue lists.