2019 Fiesta ST Line.    A couple of months ago had the Key not present warning even though the key opened the doors. The car would not start of course.  Key battery down to 2.85v so replaced it.  Yesterday, same again and battery replaced.  Two things here:  short battery life and no low battery warning which I get on the Focus.  The other key works perfectly, battery at least 2 years old.   Fortunate that on both occasions, the car was on the drive.  Anybody had this?

28 minutes ago, Freddy42 said:

even though the key opened the doors.

The door lock/unlock is a separate function to the immobiliser. One can work perfectly with out the other.

The CR2032 batteries are problem these days. It seems there are more counterfeit batteries on the market than genuine ones. The most reliable (at the moment) seem to be the Panasonic ones. Try to by them from a major supermarket (not Poundland) of a garage. Test them with a multimeter before fitting, it should be at least 3.03V anything less it's already failing.

I've had problems with these big brand Batteries as well so the last time I bought a Supermarket's own brand ones for half the price and they are still working fine.

As an added bonus, no one is going to clone them😃

Yes, I've had similar experience with short battery life and apparent "dud" batteries. On my previous Fiesta, both fob batteries lasted 3 years (got the warning on the way home from first MoT). The replacements (Duracell) only lasted 18 months and one of them failed again within days with no warning at all. 

I've just had to replace an Energizer that's only 2 years old.  Non-keyless fob and barely been used.

My other fob battery has never been changed under my ownership since 2018.  Only conclusion I can come up with is that modern cell batteries are poor quality regardless of brand now.

 

1 minute ago, TomsFocus said:

My other fob battery has never been changed under my ownership since 2018.  

I'll be interested to see what's in my wife's car (2014 and still original) when it finally goes!😀

If the battery is really critical for you, buy a brand from a well known supermarket, or even chemist. Yes, it won't be as cheap as online, but their supply chains are very robust, and they often get them straight from the branded legitimate distributor.

I shall be changing the battery for a well-known brand.  However, I'm still puzzled as to why there was no low battery warning before it failed.

57 minutes ago, Freddy42 said:

However, I'm still puzzled as to why there was no low battery warning before it failed.

In the instance I mentioned earlier one of mine failed within days of replacement with no warning. One day it worked, next day it didn't. 

I'm guessing that the warning system assumes a progressive loss of charge, whereas in that case it must have lost that crucial amount of voltage literally overnight with no time for an advance warning?

 

 

1 minute ago, Eric Bloodaxe said:

I'm guessing that the warning system assumes a progressive loss of charge, whereas in that case it must have lost that crucial amount of voltage literally overnight with no time for an advance warning?

I'm not sure how the system works, or even if there are different systems. 

The Golf kept telling me the key battery was low for months before it finally died.  But...it's not keyless entry or start, so presumably no constant radio transmission at all?  I can't see it being sent through the proximity chip as I thought that was essentially a 'fixed' item.  I suppose it could be sent via radio when the unlock button is pressed? 🤔

2 hours ago, TomsFocus said:

I'm not sure how the system works, or even if there are different systems. 

Lol, I was hoping you or Unofix might know. I've only seen the Fiesta Mk 8 system work inside the car, with ignition "on". I've had it sometimes come up immediately on activating the ignition, on other occasions part way through a journey.

Never seen a message in any previous cars of any make, but then, never had battery (12v or key) issues before my 2018 Fiesta either!.

I don't use the Ford Pass app, but wonder if that gives you a message?

 

8 minutes ago, Eric Bloodaxe said:

I don't use the Ford Pass app, but wonder if that gives you a message?

I was getting constant deep sleep messages on FordPass but can't remember seeing a fob battery message on there at all.

Regarding the Golf warning, that only came up as the ignition was switched on, which makes it look like a proximity chip connection, but I'm almost certain it can't be that.  Just coincidental that all the warning messages come up at the same time.

23 minutes ago, Eric Bloodaxe said:

I don't use the Ford Pass app, but wonder if that gives you a message

When my Fob Batteries were dying I did not get a warning on my Ford Pass App but did on the Dashboard either on entering or just after switching on the Ignition, I can't remember.

I would have thought that Ford Pass couldn't give you a warning unless you left a Key in the car permanently, once the car goes to sleep there won't be any communication until you wake the car up again.

2 hours ago, Eric Bloodaxe said:

Lol, I was hoping you or Unofix might know.

Sorry, I only partly know how it works.

Back in the days of putting a metal key in the ignition barrel it was easy to understand. The transponder chip is passive but when placed next to the loop aerial around the ignition it would be woken up with a pulse from the loop and in response the transponder chip would transmit it's code back.

The new keyless ignition system kind of uses a similar idea but has to involve the keyfob transmitter to relay the transponders code to the receiver aerial.

So, this is where my information gets a little sketchy. As I understand it, when you press the start button the car broadcasts a request signal looking for the transponder chip. This request is picked up by a receiver built in to the keyfob and powered by the battery. Upon receiving the request for the transponder code the keyfob interrogates the passive transponder and gets the code, it then transmits this code from the keyfob, which the aerial inside the car picks up. If all is good then the ignition is allowed to start the engine.

If the battery in the keyfob is weak then it either fails to detect the 'request' for the code, or more probable, it just doesn't have enough power to transmit the code to the car.

This is why when the keyfob battery is low, you can still start the car by placing the keyfob in the emergency position. This works just like the old system and a loop aerial just directly pulses the passive transponder chip and reads the code directly.

If any Ford or Ford security engineers know the exact way the system works, I'd love to know 👍