One of my keyfobs has stopped working. It doesn't lock or unlock the doors, and doesn't unlock the trunk. I took it apart, and the battery is fine - 3.1V. But the red LED on the bad keyfob doesn't flash when I press a button (it does flash on the good keyfob). So I've concluded - "It's dead, Jim". Does that sound right?

Do I have any options other than getting the dealer to replace it? I see what appear to be very similar keyfobs on Amazon, but the listing says programming the new key requires that "a device" be connected to the OBD2 port, and I have no such device. Has anyone here ever tried one of the aftermarket keyfobs, or know what kind of device is required?

Thanks for any suggestions.

 

Is the FOB part of your Civic's key?

I'm not sure how the battery makes contacts in your key fob, but I've run into cracked/broken solder joints on GM vehicles where the c-shaped clip holding the battery meets the circuit board. maybe clean up the rubber key pad where it meets the sensors on the circuit board? I've had to replace the rubber pad on my parents GM fob in the past as well.

 

Instructions:
Replace the transmitter battery (CR1616) with a new one, and try to lock and unlock the doors with the transmitter by pressing the lock or unlock button at least 10 times:
If the doors lock and unlock, the transmitter is OK.

The keyless transmitter is combined with the immobilizer transponder; so, if the key/keyless transmitter was replaced, it has to be registered into the system.

 

The problem is that the fob doesn't even flash its own red LED when I push a button. The good keyfob does do that. I think that means it isn't working at all. I've taken it apart twice to make sure all the contacts are clean, but nothing is happening. The battery is fine - 3.1V. The replacement would be something like this, but would have to be programmed:

 

Have you tried to lock and unlock the doors with the transmitter by pressing the lock or unlock button at least 10 times? It may take more tries.

Right now, in front of me, I have an unused spare transmitter that has a good battery (3.29 V) that is not registered to my car. The LED does not blink when I press the transmitter buttons.

 

Thanks for being persistent in asking me if I had done that. After reading your post, I went to the garage and pressed the lock and unlock buttons alternately 20 times, then each 20 times in a row, then the trunk button, then the panic button a few times. Then I did lock and unlock very rapidly over and over. Then as I was walking back into the house doing the final presses of - something - the doors locked. And now it works perfectly, including the blinking red LED. So I guess there's a pattern of presses that makes it re-establish the link to the car, and I must have managed to do that pattern by chance. I've found nothing online about such a pattern. Or maybe it's just doing enough of anythiing that gets it going again.

It's still a mystery as to what caused it to lose registration in the first place and stop working. But at least it's working now. Thanks very much for bailing me out on this.

 

Good to hear you have it working again.

Pressing the transmitter lock or unlock button at least 10 times is to reset the transmitter. The procedure is part of Honda's service repair manual.

 

So would this procedure always be needed after just changing the battery?

 

Usually it is not necessary when changing the battery.