Keyless System Malfunction and unable to start

I'm having an issue with my 2018 CX-5 and was hoping to get some help.

I'm unable to start the car. This is after the car was left sitting for 4 days. Initially I though it was an issue with the battery, but still unable to start even with a jump. I'm getting an error message of "keyless system malfuction" and the ignition light blinks red. I've tried replacing the keyfob battery, trying a second keyfob, holding the keyfob right up to the ignition switch, all without success.
The keyfob is recognized via pressing the button on the driver side door to lock/unlock

Any suggestions of things to try next, before I get it towed to a mechanic or dealer?
 
First did you fully recharge the battery? Then, have you tried to disconnect the negative battery terminal for a few minutes and reconnect and retest? The ECM/BCM may just need a deep restart (hope).
 
Yayy!

Not sure how old your car and battery are - if they are old you'll probably need a new battery. If not old, then go get a battery charger and hook it up for several hours. Running that low is not good for car batteries.
 
Yayy!

Not sure how old your car and battery are - if they are old you'll probably need a new battery. If not old, then go get a battery charger and hook it up for several hours. Running that low is not good for car batteries.
OP said it’s a 2018 and I assume the battery should be fine. He should bring his 2018 CX-5 to his Mazda dealer checking up the problem. Hopefully there’s some error codes saved at this time. Dealer should be able to check the battery too if the battery capacity is not within specs. The factory battery may still have some warranty left if the culprit was really the weak battery. The car should be able to start without any problem after just 4 days of sitting.
 
Take it to the dealer and say you got a 'keyless system malfuction' and have them check it out. The last thing you want is to be stranded somewhere if it happens again. It is a PITA to go, especially if it is working fine now, but you should get it checked out.
 
OP said it’s a 2018 and I assume the battery should be fine. He should bring his 2018 CX-5 to his Mazda dealer checking up the problem. Hopefully there’s some error codes saved at this time. Dealer should be able to check the battery too if the battery capacity is not within specs. The factory battery may still have some warranty left if the culprit was really the weak battery. The car should be able to start without any problem after just 4 days of sitting.
I was thinking the same thing.

For goodness sake, people take vacations and leave older cars/batteries than this sitting for a week or longer, and [rightfully] expect the battery to turn the thing over. This is not "long term storage."
 
Brake pedal switch or transmission switch could be the problem. Try moving the shift lever around and hit the brake pedal several times to see it that gets you going. Ed
 
For goodness sake, people take vacations and leave older cars/batteries than this sitting for a week or longer, and [rightfully] expect the battery to turn the thing over. This is not "long term storage."
I wonder if there is a parasitic drain when the key is left inside the vehicle while powered off. I've read of others with power issues after the keys were left in the car for multiple days. Maybe it triggers the dome light to stay on, or some other trigger?
 
I wonder if there is a parasitic drain when the key is left inside the vehicle while powered off. I've read of others with power issues after the keys were left in the car for multipledays. Maybe it triggers the dome light to stay on, or some other trigger?
My 2019 manual says:
If a key is left in the vehicle, the functions of the key left in the vehicle are temporarily suspended to prevent theft of the vehicle. To restore the functions, press the unlock button on the functions-suspended key in the vehicle.

I'm not certain what model years this applies to.
 
My keyfob battery was running low last year and the system indicated that my battery should be replaced. I can't remember the specific message...replacing the battery worked.

I left my car sitting out for 20 days while I was traveling and it started up just fine. OTOH, there was so much rust accumulated on the brake rotors that I drove it 2 miles hearing a thump thump thump until braking/driving the car cleaned off the rotors.
 
Tomorrow morning I have to diagnose a 2020 cx5 with keyless malfunction light on, I will definitely put something here, whatever I find. I will use these tips.
 
OP said it’s a 2018 and I assume the battery should be fine. He should bring his 2018 CX-5 to his Mazda dealer checking up the problem. Hopefully there’s some error codes saved at this time. Dealer should be able to check the battery too if the battery capacity is not within specs. The factory battery may still have some warranty left if the culprit was really the weak battery. The car should be able to start without any problem after just 4 days of sitting.
I would not be so sure that the battery is ok since its a 2018. We have a 2018 and battery recently tested and found to be getting weaker, but not bad enough yet to replace it.

Also, if distilled water has not been added to the battery since new, the cells may be low in water and cause the battery to fail.
 
Tomorrow morning I have to diagnose a 2020 cx5 with keyless malfunction light on, I will definitely put something here, whatever I find. I will use these tips.
@ramondallot3 So, did you diagnose that cx5 after all? ;D I've got a similar keyless entry malfunction on a 2020 CX-3 and am wondering what I could look out for before getting the vehicle out to a dealer.

- FOB batteries (main and spare) replaced, it's not the FOBs

- Vehicle battery replaced

- Key light seems fine after battery connection is disconnected & replaced (green light while pressing brakes, not illuminated while engine is running), but the problem returns after the vehicle is either manually locked or left unattended (automatically locked). red light when brakes pressed, and constantly illuminated red when engine is running

- Vehicle also becomes unresponsive to the FOB if left standing for some time, I'm guessing 30 minutes or more... I need to be very close to the vehicle hoping it will unlock. Once it's unlocked once, it continues to respond and range/distance of the reception seems normal until the vehicle is left to stand again for some time...

Quite mystifying to say the least... :/
 
Tomorrow morning I have to diagnose a 2020 cx5 with keyless malfunction light on, I will definitely put something here, whatever I find. I will use these tips.
@ramondallot3 So, did you diagnose that cx5 after all? ;D I've got a similar keyless entry malfunction on a 2020 CX-3 and am wondering what I could look out for before getting the vehicle out to a dealer.

- FOB batteries (main and spare) replaced, it's not the FOBs

- Vehicle battery replaced

- Key light seems fine after battery connection is disconnected & replaced (green light while pressing brakes, not illuminated while engine is running), but the problem returns after the vehicle is either manually locked or left unattended (automatically locked). red light when brakes pressed, and constantly illuminated red when engine is running

- Vehicle also becomes unresponsive to the FOB if left standing for some time, I'm guessing 30 minutes or more... I need to be very close to the vehicle hoping it will unlock. Once it's unlocked once, it continues to respond and range/distance of the reception seems normal until the vehicle is left to stand again for some time...

Quite mystifying to say the least... :/
Did either of you guys crack this nut?
 
Hi Calebsw,

I got my issue fixed by the dealer. Their follow-up report was as follows.. Hope it helps you in some way:

Concerns
1. Vehicle struggling to unlock with key
2. Drivers side keyless entry button not working when trying to unlock the vehicle.
3. Red key illuminates red on dash

Findings:
Plugged in MMDS and checked for fault codes - found key battery fault and fault code for exterior antenna
Removed door panel and found external antenna plug not plugged in.
Plugged in keyless entry antenna and cleared all fault codes

Result:
Keyless entry button on driver’s door is working
Red key on dash no longer illuminated permanently
Keyless entry working properly
Key locking and unlocking without fault after testing a few times

For me, the incident occured after taking my vehicle in for panelbeating repairs on the driver's side door. Turns out, the panelbeaters (who are Mazda authorized & authorized by my Insurance company, mind you) didn't plug in the antenna after completing their work, and that was apparently the problem.

Happy Christmas & Regards
 
I literally just had body work done on my car's door, and this issue presented itself when I picked the car back up earlier this week. I wouldn't be surprised if that was the case here as well. That's actually very helpful, thanks for that!
 
I'm getting this problem now, except it's keyless system malfunction, power steering malfunction, DPF, battery management, SBS, Front radar sensor, Smart city brake, BSM, Driver attention alert, vehicle system, 4WD system, front camera sensor system..
I took it to Mazda the first time it happened. They had it for a few days and just changed the battery (wasn't that old but apparently didn't pass a variety test after a few times, was low voltage).
Car worked this morning, no problems, the issue returned again this afternoon.
It's all in warranty but a real PITA.
There has been no work done to the car, not involved in any accidents.

Anyone have any ideas?
 
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