2017 Toyota Aygo

The carpet underneath the mats on the driver's side of the car became wet a couple of months ago.
I asked for the dealership to diagnose the problem, and they ruled out the windscreen and the doors.
They tell me the cause is the tailgate third brake light and it has to be replaced.

I have a hard time believing water is getting through the brake light and going to the carpets with no damage to the headliner and the boot being dry: enter image description here

enter image description here

This is after they removed the stop light and the seal on the back of the spoiler.
To me, the water would either flow outside of the car because of the boot lid rubber seals on the picture, or go to the headliner through the rubber sleeves next to the yellow circle.

I have also found two photos of the Aygo tailgate spoiler showing it doesn't share any connection to the main body of the car: enter image description here enter image description here

Am I wrong saying it doesn't seem to be the cause?

  • Welcome to Motor Vehicle Maintenance & Repair! Does the car have a sunroof? Commented Jan 25, 2023 at 18:22
  • @Pᴀᴜʟsᴛᴇʀ2 No sunroof, no water damage on the headliner.
    – gstorto
    Commented Jan 25, 2023 at 18:36
  • Water infiltration can be hard to locate. The usual place it to run water over the car while you or an assistant poke around inside until you find the water patch. But it looks to me to be improbably that the 3rd light is the source.
    – jwh20
    Commented Jan 25, 2023 at 18:42
  • 1
    Agree with jwh20 on the 3rd brake light. The hoodliner wouldn't necessarily be getting wet if the drain was plugged on a sunroof. I've seen it run right down the A-pillar and out onto the floor without ever touching the head liner. It was just a thought, especially since you said it is only showing on the one side. Commented Jan 25, 2023 at 19:14
  • The rear brake light seal may have dried out and shrunk, allowing rain water to seep into the cavity and into the two harnesses to seep into the interior. Is the left side tube a drain? If there's a drain tube then the tube and drain passage may be blocked. If corrosion hasn't begun to rust, a new seal or careful application of silicone sealant on both sides of the seal should stop water infiltration.
    – F Dryer
    Commented Jan 25, 2023 at 21:07

1 Answer 1


Toyota says water ingress through the brake light will fill the spoiler up to a critical level. Beyond this level, water goes down the rubber sleeve on the right. It is channeled to the carpets driver's side.

  • That's interesting. Is there any documentation which shows this? What is the "critical level"? Commented Jan 29, 2023 at 1:27
  • @Pᴀᴜʟsᴛᴇʀ2 no, everything was over the phone. If you see the pictures, the rubber sleeve sits higher than the bottom of the spoiler. If the water level inside the spoiler reaches the rubber sleeve, the water will be channelled down.
    – gstorto
    Commented Jan 30, 2023 at 14:41
  • I guess my bigger question is, why does water ingress into the spoiler in the first place? Commented Jan 30, 2023 at 14:50
  • @Pᴀᴜʟsᴛᴇʀ2 According to them, it is due to the stop light having a leak. They say the hollow stop light and the stop light lamp have to be replaced (two separate parts).
    – gstorto
    Commented Jan 30, 2023 at 14:57
  • Sounds like a very nice job for some clear silicone sealant. Commented Jan 30, 2023 at 14:59

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