2015 Ford Fiesta ecoboost

key in ignition,going to start car, no key detected,will start sometimes and not sometimes. Urghhhh help please Thanks

What happens with you 2nd key?

Is there a battery in the key?

7 hours ago, Tiexen said:

What happens with you 2nd key?

Same as other key

7 hours ago, Bobr said:

Is there a battery in the key?

Yes new in both

Did you change the batteries in the key before the problems started or after?

 

22 minutes ago, Tiexen said:

Did you change the batteries in the key before the problems started or after?

 

After problem started

After problem started

I have had this problem with a push button start car recently and it has turned out to be the BCM.

This site not much help

key transponder fault 

Very hard to diagnose problems with minimal information. Valid solution given at minimal cost of a battery.

Are both keys faulty then or is it the immobiliser.

Solved "Key not detected" issue. 

Hi. This is how I solved this issue on a fiesta with pretty much the same spec. Having the same intermittent issue with whichever of the two keys used, both of which lock and unlock the doors perfectly which generally means it's not a key fob battery issue. When it happens you get the dreded error message on the display saying "Key not detected". If lucky, the for some people it clears itself, (sometimes quickly and sometimes not so quick) and the car can eventually be started. 

To cut a long story short, the fix that worked for me (and is still working with no issues one month on) was to replace the key antenna/transponder array assembly located around the key entry point on the steering column. Using the details stamped on it I located an identical good second hand unit from ebay (£25)  and fitted it. Removing the covers on the steering column was easy (many vids available online showing the process), one clip to detach the wires to the old antenna, and then the antenna itself can be carefully pulled/unclipped away from the column. 

Reverse the process to fit the replacement. 

That's what worked for me. 

Hope it helps others to solve similar issues.