Really after some help. Yesterday my 2014 fiesta st3 wouldn't detect any of the 2 keys I have for it. After a while it finally did and I got it started. When I arrived home I changed both batteries in the fob but the problem still persists. It also will not lock from the outside. Can anyone point me in the right direction before I have to go to ford and empty my bank account? Thank you 

 

 

 

 

 

 

 

 

 

 

 

 

Start with the easy things first. Put the car battery on charge for at least 8 hours. Make sure you connect the negative lead of the charger to the chassis main earth point and NOT the battery terminal.

There are two functions of the keyfob and they are totally separate. (a) There is the passive transponder chip. It does not require a battery, and this is what the car's ignition reads to determine if the key is correct and allows the car to start. (b) There is the remote lock/unlock of the doors either by pressing the buttons on the keyfob or if keyless entry by it transmitting a signal so the car detects the fob and allows the doors to be opened. - This function does use the battery (Duracell CR2032) in the keyfob.

If the car is not detecting the keyfob's to allow it to be started then the problem is with the passive transponder chips. When the car battery state of charge falls too low it can cause problems with the keyfob being detected.

Thank you I will start with the battery and see how I get on 

 

 

 

 

 

 

 

 

With a flat remote batteries or not,  the car should start instantaneously if remote fob is placed here. 

That's assuming the 12v car battery is ok. 

On 3/5/2022 at 4:05 PM, unofix said:

Start with the easy things first. Put the car battery on charge for at least 8 hours. Make sure you connect the negative lead of the charger to the chassis main earth point and NOT the battery terminal.

There are two functions of the keyfob and they are totally separate. (a) There is the passive transponder chip. It does not require a battery, and this is what the car's ignition reads to determine if the key is correct and allows the car to start. (b) There is the remote lock/unlock of the doors either by pressing the buttons on the keyfob or if keyless entry by it transmitting a signal so the car detects the fob and allows the doors to be opened. - This function does use the battery (Duracell CR2032) in the keyfob.

If the car is not detecting the keyfob's to allow it to be started then the problem is with the passive transponder chips. When the car battery state of charge falls too low it can cause problems with the keyfob being detected.

But what's the likelihood of BOTH key transponders having the same fault at the same time?

We have a similar problem with intermittent "key not detected" and "key fob battery low" warnings.

Have tried a BMS reset but that hasn't helped. So, a bit stuck for inspiration.

I'm beginning to suspect the problem lies within the vehicle not the key fobs after changing the fob batteries several times over a short period.

Anyone know where exactly the modules are located on a 2013 Ford Focus mk3 that process the signal(s) from the key fob?

ps I take your point about the vehicle main battery condition and will put it on charge to see if it makes any difference.

17 minutes ago, autocat said:

We have a similar problem with intermittent "key not detected" and "key fob battery low" warnings.

The passive part of the keyfob is the transponder. If the vehicle is not detecting the transponder the problem is with the vehicle not the keyfob.

17 minutes ago, autocat said:

But what's the likelihood of BOTH key transponders having the same fault at the same time?

Zero. As said above the transponders are passive. The problem is with the car.

It is extremely important that the car battery is fully charged. Using a multi-meter measure the voltage at the battery terminals after the car has been parked for 1 hour. A healthy fully charged battery should be 12.65V anything less than 12.50V and the battery is not in a fully charged condition.

Resetting  the Battery Monitor System (BMS) will not help the situation. You need to use a Smart Battery charger. Connect the positive charging lead directly to the battery terminal. Connect the negative charging lead to the chassis earth point, NOT the battery terminal. Leave the battery on charge for 12 hours.

My issue is a bit different.  RFID chip fell out of fob.  Found the chip and replaced it in the fob.  But it seems the vehicle will no longer recognize the RFID chip.  Fob works great but key with chip says the key is not detected.  The chip was not damaged and my spare fob and key work just fine.  I suspect the chip fell out of the car while being driven and that the programing in the car's computer disabled the chip when it could no longer detect it present and that the key will need to be programmed to the vehicle a 2nd time.  That's my guess..

A locksmith showed me the proper orientation for the RFID chip and now the key is working again.  Thank you all.

2012 ford focus MK3 1.6 tdci (keyless start) with same problem of "no key detected" and unable to unlock/lock vehicle.

Root cause was the RF keyless antenna (if you have ForScan you'll see a U201F-13 DTC).

Finding it was the problem, it actually lives just above the drivers visor right beside the centre console support. To get access to it, you need to push the centre console clips and drop out the back section (furthest away from windscreen section). It could be easier to work from the section nearest the windscreen to get the panel out - I worked from the section nearest the passengers. Take your time and it'll come out without any breakages. Then with thin hands reach into the void behind the black plastic structure's leg supporting the centre console (in the direction of the drivers sun visor). You can just see the back edge of the RF antenna black plastic box at an acute angle right behind the support if you're uncertain. It's held in place by some hot glue, you'll need to twist the whole unit to get it unstuck. Once you've done that you can move it out (there's enough play in the wires) before disconnecting the wiring plug. Fitting is the reversal, no coding is required - just plug new one in, test the unlock button works and you're good to go.

You can drive the car without the unit however you'll need to use the physical key & fob for unlock/lock and starting (user manual will explain). Reminder - If you open the car with engine running it will moan because it cannot detect the key ([OK] will clear) but not clear the i red logo until restarted ! No issues on driving car during time I was waiting for part, only to put keyfob near detector when first entering car and pressing stop/start to avoid alarm..

Hope these pictures help others with the the part, location and some of the plastic clips.