Car wouldn't start, not sensing the remote key

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CX5 GT
My girl said her remote wasn't working so I installed a new battery. Car wouldn't start this morning with either remote key. Both batteries had over 3 volts. I put the key right next to start button and it eventually started. Also either remote would not activate the door locks.

Could there be an issue with the "receiver" that accepts the signals from the remote key?

Thanks.. Tim
 
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2020 CX-5 AWD
Did you test the vehicle's battery? It's the place to start for any undiagnosed electrical issue.
 
Hi Tim. Something similar happened a few months back on my CX-9. Only difference is I was able to lock and unlock my doors with the fob. Turned out the key fob was 'asleep'. I just had to wake it up following the procedure described in this video. Hope this helps

 
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2018 CX-5 Sport
Are you sure the fob battery is good? When my fob battery was running down, it would unlock my car but my car wouldn't start. Then suddenly it would. It nearly tricked me into thinking the car's receiver was going bad. New batteries corrected it.
 
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CX5 GT
It would only randomly start. It is with a mechanic at the moment. I did install new batteries in both fobs. Checked with my Fluke @ +3.2v.

Thanks. Will check back when I find out what it is.

It's a 2016.5 sorry. No buttons on the side of fob..
 
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CX5 GT
Mechanic said he put a new battery in her fob and everything started working, door locks and startup. I checked my fob with the same battery in it as when it did not work, and it worked fine, door locks and start. Seems strange, doesn't make sense.. we'll see what happens I guess.

Thanks for your help.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Mechanic said he put a new battery in her fob and everything started working, door locks and startup. I checked my fob with the same battery in it as when it did not work, and it worked fine, door locks and start. Seems strange, doesn't make sense.. we'll see what happens I guess.

Thanks for your help.
Thanks for the update. It’s strange that the key fob didn’t work when you put in a new battery, but your mechanic did it and everything suddenly works! But this kind of thing happens though. My guess is somehow something got reset by your mechanic which makes everything going back to normal with new key fob battery. Or there’s bad connection when you installed the new battery. Could you see the tiny red indicator on the key fob lit when you pushed any buttons after the new battery was installed? That red LED on the key fob is a good indicator making sure your new battery is properly installed.
 
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CX5 GT
Yes, both fobs had the red indicator light up when any button was pressed. I do not feel the 3V fob batteries were bad.

One theory is since the mechanic is the one who works on her employer's company trucks, he may have told him to take care of it and not charge her. He is that kind of guy and he won't tell her if he did... I am curious though because it does not make sense.

it all appears to be fine now so we'll hope for the best, thanks again... Tim
 
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Mazda
I have a similar issue where the key fob would work one day and not the next. The fob wouldn't unlock the doors but would start the car just fine. Well, I was driving, the key fob slipped out of my pocket and onto the seat and I didn't notice and locked the doors. I had to have someone drive a spare down 20 minutes away.
 
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