Keyless entry VERY slow to respond.
 

My 2013 BRZ has been with me for about 4 years now. The keyless entry has been pretty easy to use. However, starting from 1 month ago, sometimes it becomes very slow to respond. For example, I have to stay near the door for about 2 minutes this morning for it to respond. Once it worked for the first time, it worked well for the rest of the day. So I think it should not be a battery problem with the key or the car battery. The symptom is mostly consistent with the wireless unit inside the car cannot 'wake' immediately when the key is nearby. It might go into a 'sleep' mode overnight.

Has anybody had similar experience before and what is likely the cause or solution for this problem? Thanks a lot for the help. It is quite annoying to wait a while every morning.

Don't automatically rule the fob battery out. A low battery can do some weird things and 4 years is a long time for a remote one to last. Change the battery before trying to figure out anything else.

Electrical/electronics trouble shutting hierarchy is power source, connections, components.

Ok. Thanks. I remember I have another key lying around somewhere which I never use. Maybe I shall try that key first to make sure it is not battery related. BTW, with my key, there is also another very small black key, does anybody know what is that key for? Thanks a lot.

Even though you have never used it the battery in it is 4 years old as well. They don't have an infinite shelf life.
The small black one is the valet key. It won't open the trunk.

Yep -- Your fob battery is almost dead. If you have to sit there waiting for it to detect your hand for more than a second or two it is the battery. I couldn't believe it either until I replaced my batteries (buy from amazon) -- good as new.

PS: even if your fob battery is completely dead the door (and the start button) can send a tiny RFID signal to your fob to power it/unlock the door. This ensures that you don't become stranded if you have a dead fob. If you are waiting a long time for the door to unlock it is likely that the fob is eventually receiving power from the RFID signal (thus the battery isn't doing its job like normal).

If it is the battery in the fob, how can we explain the fact that the remote works quite well for the rest of the day?

I have no idea what to tell you there -- Except that I experienced the exact same thing. I had it work, on and off, for a period of a few weeks and then it finally decided to quit.

We can solve this mystery simply by changing the battery. That's my recommendation.

If your battery is completely dead, it will not unlock the car door. You have to use the little key in the key fob. Then prepare to jump in and hold the fob next to push button start and get the engine started so it will shut off the alarm.

Thanks for bringing this up. Here

https://en.wikipedia.org/wiki/Radio-...identification

RFID tags contain at least three parts: an integrated circuit for storing and processing information that modulates and demodulates a radio-frequency (RF) signals; a means of collecting DC power from the incident reader signal; and an antenna for receiving and transmitting the signal. The tag information is stored in a non-volatile memory. The RFID tag includes either fixed or programmable logic for processing the transmission and sensor data, respectively.

Is it possible that the key works for the rest of the day b/c it collected some energy from the reader (in the car) while I drive? Fascinating. Anybody knows about the details?

I had issues with mine being able to read the fob from inside the car for many weeks. A new fob battery did nothing. My car battery died when I left it at Subaru over the weekend for some warranty work, and that got me thinking that perhaps the sensor array in the car was sensitive to reduced voltages, and that my issues were actually a heads up that my OEM battery was on its way out.

New car battery and I no longer had any fob issues. And yes, my fob issues tended to be more likely to occur after the car hadn't been driven for longer periods of time - because the battery would be topped of immediately after any drive, and so caused no issues during brief periods of inactivity.

Thanks. But hopefully you are wrong. This is a $100 vs. $4 issue. I have ordered new key fob batteries. Let's see what is going to happen after I change the fob battery first.

What year is your car?

^