Anyone have any ideas as to what is going on here?

My wife has a Mazda5 van. I recently changed the battery in her keyfob (changed only like 1 year prior) because she was complaining "it wasn't working again".

What's strange is the keyfob seems to work intermittently, some days it's fine but other days it doesn't seem to want to work.

I noticed that during that stretch of really brutally cold weather we had from end of December to mid-January with single digits and below zero at night, it wasn't hardly working at all. Now it's back to more seasonable mid-30's to mid-40's and it seems to be working better but is still a little flakey.

It seems to be affected by cold? Is this her battery? Is the fob itself going bad? I hope not because they are like $180 from the stealership.

The only thing I can think of is the battery is going dead - but they shouldn't go bad in a year.

Does she use the fob to lock/unlock the doors? We don't, so maybe that's why ours last longer. We got into the habit of using the on-door lock/unlock buttons rather than the fob since that sends no signal that can be picked up by someone with a scanner.

Also, even if the fob battery is dead, the car is supposed to start by using the fob to press the start button. So, as long as you can get into the car, you shouldn't be stranded.

I can't even say water getting into the fob would do that, because I had a wave run up the beach and soak mine in salt water and it's still working fine over a year later.

That's what they wanted to charge for a new key fob for my Nissan so I picked up a couple from Amazon for under $10 a piece and found a youtube video how to program it.

Here a video for a Mazda and mine was similar to the steps to program it.

https://www.youtube.com/watch?v=z7V3FH_uB6U

Another suspicion, based on the cold weather factor, is that one of the battery contacts is only making partial contact. Things contract when they get cold and an "iffy" contact becomes no contact.

quote:

Originally posted by WaterburyBob:


Also, even if the fob battery is dead, the car is supposed to start by using the fob to press the start button. So, as long as you can get into the car, you shouldn't be stranded.

It's a fob with key attached, she uses it to unlock/lock the car and the key to start it, it's a 2012.

I've heard that corroded internal antennas causes those intermittent connectivity problems on Mazdas. That's why the problem changes with the weather.

We had a similar problem in our Mazda 5 and it turned out there was a faulty switch in the
automatic gear shifter.

quote:

they shouldn't go bad in a year

The original batteries for my '04 are still going strong.

Mine wasn't weather-related, but my 2000 Acura TL did similar, with intermittent functionality with the remote.
Pretty sure it was due to insufficient button contact internal to the remote. But, it was also in pretty rough shape.

is the battery contact broken/loose going into the circuit board?

this is a notorious problem with Dodge key fobs

quote:

Originally posted by k5blazer:
We had a similar problem in our Mazda 5 and it turned out there was a faulty switch in the
automatic gear shifter.

This does happen. Two or three times in 15 years, I've been unable to start my Nissan... key turns, lights come on, starter doesn't spin. Hold the brake, run the shifter from Park to Neutral and back again, twist the key, and all is well.

What about the other fob, you should have gotten two.

Cold weather kills alkaline batteries. Check to see if you can get a lithium battery for the remote.

I'd suggest trying the other fob. If it works switch the battery with the first. Maybe a bad battery? Maybe a bad connection?
My 2014 CMAX fob started going. It was intermittent and took several tries to open. I took the second fob and no problem. The Ford guys pointed out that, as the fobs were the same age, I'd do well to change the other battery.