Key Fob stopped working, now battery is draining

[Omodaka]

Hello, 
My key fob, stopped working. The buttons are worn out. I dropped by the Toyota dealer, and they said it needs to be replaced. 
Now, a few weeks later, my battery has been very weak (the car would eventually start), but now the car is dead. 

Is there a correlation between the battery, possible drain, and a broken key fob?
I live in NYC and can't afford to spend $$ going in the wrong direction (replacing the battery/searching for a drain/replacing the key fob) if one isn't necessary.

Thanks for your help

[RX400h]

Quote

It’s unfortunate that your key fob stopped working, and now you’re dealing with a weak battery. Let’s explore the possible correlation between these issues:

1. Key Fob and Battery Drain:

   • A key fob communicates with your car to perform functions like locking/unlocking doors, starting the engine, and activating the alarm. When you press a button on the key fob, it sends a signal to the car.
   • Consumer Reports explains that while the key fob does cause a slight drain on the battery, it generally won’t completely drain a healthy car battery. The key fob’s constant communication is a factor, but an old or aging car battery is more likely the root cause.
   • In some cases, if the key fob battery is old or defective, it may send a weak signal to the car, leading to continuous attempts to receive the signal. This can contribute to battery drain.

2. Car Battery Health:

   • Your car’s battery strength directly affects the key fob’s performance. A robust car battery ensures optimal operation of electronic systems, including the key fob receiver. Conversely, a weak car battery can result in decreased key fob range or responsiveness.

3. Next Steps:

   • Before replacing anything, consider these steps:
     • Check the Car Battery: Have your car battery tested. If it’s weak or old, replacing it might solve both issues.
     • Inspect Key Fob Battery: Replace the key fob battery if it’s worn out. It’s an inexpensive fix.
     • Address Key Fob Buttons: If the buttons are worn out, consider repairing or replacing the key fob.
     • Look for Parasitic Drain: If the battery continues to drain, there might be a parasitic drain (e.g., faulty wiring, malfunctioning components). A mechanic can diagnose this.

Remember, I’m not a mechanic, but these general guidelines might help you avoid unnecessary expenses. If you’re unsure, consult a professional to diagnose the specific issues in your car.