I have been having an issue with the central locking working from the remote fob. 

I have a 2005 Mondeo ST 220 

 

The central locking is now becoming very temperamental when you are using the fob to unlock it. Sometimes it can take up to 2 minutes to lock or unlock the car by holding or repeatedly pressing the fob and other times opens first time. There is clearly an issue somewhere and I was wondering if anyone knew a solution? 

 

I have replaced battery in the fob and this has not rectified it. 

Well, most likely it's the switch behind the button on the fob itself. I know you can buy replacement switches for generic fobs on ebay, you  have to solder them in. Apart from that, if you replace the whole fob, you have to program the new fob for the central locking, but also there's the immobiliser chip that needs to be programmes to the ecu too. 

Something here on programming the key

https://www.fordwiki.co.uk/index.php/PATS_Key_%26_Keyless_Entry_Programming

 

3 hours ago, Tyrfing said:

I have replaced battery in the fob and this has not rectified it. 

I know you've said you have replaced the battery, but before you go down the rabbit hole of investigating everything else, you should get a multimeter and ensure your new battery is throwing out about 3.3v. Once that's confirmed, then you can spend your time with further diagnosis...

1 hour ago, StephenFord said:

you should get a multimeter and ensure your new battery is throwing out about 3.3v.

Do you doubt the quality of 'Poundlands' pack of 5 for a £1 🤣

1 hour ago, unofix said:

Do you doubt the quality of 'Poundlands' pack of 5 for a £1 🤣

Now where have you been? With inflation, you only get 4 for a £1 now LOL

Cheers, I'll try and see 👍