Erratic Start Problem CX-5 2015

Harlyn

Member
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CX-5 2015 AWD
Just replaced our 2014 CX-5 with a 2015 CX-5 AWD. Problem occurred within first 100 miles. (5 times) On occasion it will not start, towed to dealer today, and of course it started there. Dealer had over last weekend, no problems. Happens sporadically, then after trying for a numerous times will start. Red light on key fob and brake pedal pushes hard. Dealer said they checked battery on Fob, brake relays, etc. They called Mazda, no help there, no stored codes. Anyone else experience this problem? Ready to give car back and get 2014 CX-5 back.
 
This may seem way too simple, but could it be a bad battery in the FOB? Next time it won't start try physically touching the FOB to the start button and see. If that's not the issue, it seems like it could still be a smart key communication problem of some sort.
 
Could be a frozen relay. Mine had similar issue. Dealer replaced few relays and it fixed the problem.I think there is a tsb for it.
 
I also vote the fob. When we bought our 2014 the first one died on my wife in less than a year. My wife did not know about holding the fob to the button so the car was dead. I was fortunate enough to notice a low key battery warning over the weekend and quickly changed my fob battery. I never had fob batteries die so easily in my past velhicles so I would encourage everyone to change them yearly. Tell the dealer to physically change the battery, just checking it is worthless!
 
Just replaced our 2014 CX-5 with a 2015 CX-5 AWD. Problem occurred within first 100 miles. (5 times) On occasion it will not start, towed to dealer today, and of course it started there. Dealer had over last weekend, no problems. Happens sporadically, then after trying for a numerous times will start. Red light on key fob and brake pedal pushes hard. Dealer said they checked battery on Fob, brake relays, etc. They called Mazda, no help there, no stored codes. Anyone else experience this problem? Ready to give car back and get 2014 CX-5 back.

Welcome to the forum!

I'm confused when you say "Red light on key fob and brake pedal pushes hard."

Do the 2015's have a red light on the key fob? It's hard to diagnose your trouble with such a cryptic description. Please say what you mean rather than expecting us to assume things. Diagnostics and assuming do not go well together.

When I first brought home our 2013 CX-5 it would not start for my wife. Every time I tried it started like clockwork. We never did figure out what she was doing wrong but she hasn't had a problem since. It doesn't make sense that she was doing it correctly but it wouldn't work (because it's been starting flawlessly for over two years now) so we have attributed it to operator error.
 
I also vote the fob. When we bought our 2014 the first one died on my wife in less than a year. My wife did not know about holding the fob to the button so the car was dead. I was fortunate enough to notice a low key battery warning over the weekend and quickly changed my fob battery. I never had fob batteries die so easily in my past velhicles so I would encourage everyone to change them yearly. Tell the dealer to physically change the battery, just checking it is worthless!

I just had to change one of my fob batteries today as well.
 
Possible Solution

Just replaced our 2014 CX-5 with a 2015 CX-5 AWD. Problem occurred within first 100 miles. (5 times) On occasion it will not start, towed to dealer today, and of course it started there. Dealer had over last weekend, no problems. Happens sporadically, then after trying for a numerous times will start. Red light on key fob and brake pedal pushes hard. Dealer said they checked battery on Fob, brake relays, etc. They called Mazda, no help there, no stored codes. Anyone else experience this problem? Ready to give car back and get 2014 CX-5 back.
 
After a discussion with the dealer and Mazda it was thought that not enough pressure was applied to the brake pedal to allow a signal to trip the relay. Apparently slightly more pressure is required with this particular car than was with the 2014 CX-5 she had. Will see if that explanation holds up in the future. Never had a problem with the 2014 CX-5 in two years with starting. Thanks for all the suggestions.
 
After a discussion with the dealer and Mazda it was thought that not enough pressure was applied to the brake pedal to allow a signal to trip the relay. Apparently slightly more pressure is required with this particular car than was with the 2014 CX-5 she had. Will see if that explanation holds up in the future. Never had a problem with the 2014 CX-5 in two years with starting. Thanks for all the suggestions.

You could try this. When your issue happens press the key fob to the start button, this rules out the car side of the issue and isolates to the key fob(internal issue or battery for the fob)

And if that doesn't work, release the brake pedal and press down on it again and, again, press the start button with the fob again.

Intermittent issues are real pain to diagnose and duplicate, any info you can gather is sometimes a big help for dealers and techs.
 
haven't looked at the brake switch on the mazdas, but on many cars there is some adjustment to where the pin is located. It can be moved in or out a bit to adjust for pedal travel. If that is the case on the CX-5, the pin could be moved out a bit and allow the switch to be activated with less brake pedal travel
 
Does the start button light go green when you push the brake? If it does I think this should eliminate the brake switch. As mentioned you could watch for the green light and keep trying the brake to see if you can catch a no green light situation.
 
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Remove the emergency key from the fob and pry open with a flat head screwdriver. Youll see a black disc, pop that open and the battery should come out. Replace with a new battery and reverse the steps. Just make sure that black disc is nice and snug, and the rubber o-ring is in place.
 
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