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2020 Highlander Smart Key Not Always Detected - Push Start Issues

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Christine P. · rep 0 · May 22, 2:18 AM · 1 replies · solved · Question

Vehicle: 2020 Toyota Highlander Limited

I'm having an intermittent problem with the smart key system on my 2020 Toyota Highlander Limited. Sometimes, when I try to start the car, it says "Key Not Detected" even though the key fob is right there in the cabin, usually in the cup holder or my pocket. I have to press the start button multiple times or hold the key fob right up to the button for it to work.

I've replaced the key fob battery with a brand new one, but the issue persists. It's really frustrating when I'm in a hurry. Is this a common problem with the 2020 Highlanders, or could it be something specific to my vehicle? I don't have any other electrical issues.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 2:18 AM

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ClearTheCode admin answer:

Intermittent "Key Not Detected" messages on your 2020 Toyota Highlander Limited, especially after replacing the key fob battery, point to a few potential areas within the smart key system. This system relies on a network of antennas and a control unit to communicate with the key fob.

Here are the most common causes and diagnostic steps:

  1. Key Fob Battery (Even New Ones): While you've replaced it, sometimes new batteries can be faulty or have a low charge. Ensure you used a high-quality CR2032 battery and that it's inserted correctly. You could try another new battery just to rule it out completely.
  2. Interference: Electronic devices in the car (like phone chargers, dash cams, or even other key fobs) can sometimes interfere with the smart key's signal. Try removing all other electronic devices from the cabin and see if the issue persists.
  3. Smart Key Antennas: Your Highlander has multiple antennas located throughout the cabin (e.g., in the center console, cargo area, and near the ignition button) that detect the key fob's signal. If one of these antennas is faulty, has a loose connection, or is obstructed, it can cause intermittent detection issues. This is a common point of failure.
  4. Wiring Issues: The wiring connecting the antennas to the Smart Key ECU (Electronic Control Unit) could be damaged or have a loose connection. This would require a professional inspection.
  5. Smart Key ECU: The Smart Key ECU is the central control unit for the system. A fault within this module could lead to intermittent communication problems. This is less common but possible.

When to See a Shop: If trying a different new key fob battery and checking for electronic interference doesn't resolve the problem, it's best to take your Highlander to a Toyota dealership. They have specialized diagnostic tools that can read codes from the Smart Key ECU, test the signal strength of the antennas, and pinpoint which component (antenna, wiring, or ECU) is causing the intermittent detection issue. Since your vehicle is a 2020 model, it may still be under the factory warranty, which would cover these types of repairs.

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