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2017 RAV4 Blind Spot Monitor Malfunction After Rain

0

Mike T. · rep 0 · May 25, 1:27 AM · 1 replies · solved · Question

Vehicle: 2017 Toyota RAV4 XLE

Hi all,

I've got a recurring issue with my 2017 Toyota RAV4 XLE. Whenever it rains heavily or after I take it through a car wash, my Blind Spot Monitor (BSM) system malfunctions. I get a warning light on the dash, and the system just stops working.

Once the car dries out, it usually starts working again after a day or so. This has happened a few times now. Is this a common problem? Could water be getting into the sensors or wiring?

Any ideas on what I can check or if this points to a specific component failing? It's really annoying, especially in bad weather when I need it most.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:27 AM

0

ClearTheCode admin answer:

It sounds like your 2017 RAV4's Blind Spot Monitor (BSM) system is experiencing issues related to water ingress, which is a common complaint for exterior-mounted sensors. Here's what's likely happening and what you can do:

  1. Sensor Location and Vulnerability: The BSM system uses radar sensors typically located inside the rear bumper, behind the bumper cover. These sensors are designed to be weather-resistant, but prolonged exposure to water, especially high-pressure sprays from a car wash, can sometimes compromise their seals or connections.
  2. Water Ingress: Water can get into the sensor housing itself, or more commonly, into the wiring harness connectors leading to the sensors. This can cause a temporary short circuit or corrosion, leading to the system fault. Once it dries, the connection is restored, and the system works again.
  3. Corrosion or Damage: Repeated water exposure can lead to corrosion on the sensor terminals or within the wiring harness. It's also possible a sensor has sustained minor impact damage that compromised its seal.

What you can check:

  • Visual Inspection: Carefully inspect the rear bumper area for any signs of damage or loose bumper clips that might allow excessive water entry. If comfortable, you might gently pull back the bumper cover to visually inspect the BSM sensor modules and their wiring harnesses for signs of water, corrosion, or looseness.
  • Clean Sensors: Ensure the exterior surface of the bumper where the sensors are located is clean and free of dirt, mud, or ice, though this is less likely the cause if it only happens after rain/wash.

Common OBD Codes to look for:

  • B2201: Blind Spot Monitor System Sensor (Right) Malfunction
  • B2202: Blind Spot Monitor System Sensor (Left) Malfunction
  • B2203: Blind Spot Monitor System Communication Error

When to see a shop:

  • If the issue becomes more frequent or doesn't resolve after drying.
  • If you're not comfortable inspecting the bumper and wiring yourself.
  • A professional can use a diagnostic scanner to read specific BSM fault codes, which will point directly to the problematic sensor or module. They can also perform a thorough inspection for water damage, repair wiring, or replace a faulty sensor if necessary.
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