Symptoms
- Warning lights or malfunctions appear only in wet weather
- Problems go away once the car dries out
- Specific systems (lights, windows, infotainment) act up after a wash
- Musty or electrical smell after rain
Likely causes
- CommonWater intrusion into a wiring connectorConnectors near the engine bay, trunk, or under carpets can let water in if seals are worn or damaged.
- CommonClogged sunroof or cowl drain causing water to pool near electronicsBlocked drains can direct water toward modules instead of away from the car.
- PossibleDoor or trunk seal failure letting water reach wiringA degraded rubber seal can allow water to reach interior wiring harnesses.
- PossibleWater reaching a control module directlyModules mounted low in the engine bay or under seats can be affected by water pooling.
What to do
- Note exactly which systems act up and whether it's consistently linked to rain or washing.
- Check door, trunk, and sunroof drains for clogs, since blocked drains are a very common cause.
- Inspect door and trunk seals for visible gaps, tears, or hardened rubber that no longer seals well.
- Check under carpets (especially front footwells) for dampness after a rainstorm.
- Avoid parking with windows cracked or sunroof open during rain until the issue is resolved.
- Let the car dry out fully in a warm, ventilated area if water intrusion is suspected.
- Have a shop pressure test or water test the vehicle to pinpoint exactly where water is entering.
- Get any affected module or connector professionally dried, cleaned, or replaced as needed.
Tools and parts
- Flashlight
- Shop vacuum (for water removal if needed)
When to call a pro
Water intrusion into electrical systems can cause long-term corrosion damage if not found and fixed promptly; a shop with a water test can locate the source precisely.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.