Does leaving the car window open in the rain affect the vehicle?

[LukeMarie]

Generally speaking, a small amount of rainwater entering the car or even a large-scale water intrusion will not damage the internal wiring system of the vehicle, nor will it affect the mechanical system. Here is relevant information: 1. Reason: Because the car's electrical system is protected by sheathed wires, problems are unlikely to occur easily. If abnormal headlights or other functional abnormalities are noticed while driving, it is advisable to have them inspected and repaired promptly. 2. Treatment method: If the electrical equipment is not affected, simply going to a 4S shop for a drying treatment is sufficient, and generally, the issue is not serious. If rainwater has seeped into the carpets or floor mats, they should be taken out, cleaned, and dried. After addressing the water accumulation issue, it's also necessary to sterilize and disinfect the interior of the car to prevent lingering odors.

[DiMary]

Last time it rained, I forgot to close the car window, and the entire interior got flooded. I ended up spending several hundred dollars on cleaning. When rainwater seeps into the cabin, it not only soaks the carpets and seats but also poses a bigger problem—the hidden wire connectors in corners can slowly rust, especially the wiring under the seats and beneath the floor mats, which is particularly vulnerable. Moisture in these areas may cause power windows to malfunction, door controls to act up, or the ABS light to turn on for no reason. The worst part is that lingering rainwater can lead to mold growth inside the cabin, and that musty smell won’t go away even after airing it out for three days. A water-damaged car typically loses $20,000–$30,000 in resale value, and if the electronics are affected, the repair costs can be even more shocking.

[DeThomas]

My relative's car once got caught in the rain. Don't think it's just about wet seats—the real damage happens to the delicate components inside the dashboard. Rainwater can seep through the control panel gaps into devices like the CD player and navigation unit. More insidiously, electronic parts under the seats, such as the power seat adjustment motors, can get moldy and jam. After rainwater evaporates from leather seats, salt residue forms along the stitching, leaving white marks visible within months. Memory-function power seats exposed to water may have their entire memory modules ruined. Once dried, always check if the sunroof drain holes are clogged—otherwise, water can accumulate inside the door panels.

[DelMolly]

The impact of rain on a car can be categorized into several levels. The most superficial is interior damage, such as fabric seats clumping and fading, or wood-grain decorative panels bubbling. Deeper issues involve mechanical components; for example, after rain, windows may squeak when rolled up due to water and sand mixture in the tracks accelerating wear. The most severe impact is on electronic systems—my car's wipers malfunctioned after rain, and upon inspection, it was found that rainwater had seeped into the BCM (Body Control Module), corroding the circuit board. Additionally, if the drainage holes at the bottom of the doors are blocked, rainwater can accumulate in the door's metal layers, potentially causing rust holes in less than three years. I recommend airing out the car doors for a full 48 hours after any rain exposure, regardless of the amount.

[Kai]

After experiencing two instances of forgetting to close the windows during rain, I've summarized the following lessons: Rainwater entering through the windows flows to the lowest point, which is the footwell of the rear seats. The water first seeps into the sound insulation layer, creating a breeding ground for mold. Upon removing the rear seats, I discovered that the sound insulation layer beneath the carpet absorbs water like a sponge and is difficult to dry. Even worse, the rear section of the car hides the airbag control module, and prolonged moisture can cause internal components to fail. The circuit for the overhead reading lights is also prone to short circuits and malfunctions. Rainwater mixed with dust forms a sticky, muddy grime that gets stuck in the air conditioning vents, fostering bacterial growth and causing a musty smell when the AC is turned on. It's best to perform a thorough interior cleaning within four days.