Intermittent won’t start fault car lock symbol

[Paj 77]

Hi, looking for some help with regards to a 2012 ka intermittent fault. The car lock symbol comes on and won’t start. This is an intermittent fault. Anybody know what this could be? 
thanks 

[unofix]

The car ignition immobiliser is unable to read the passive transponder chip inside the key.

Take the car key off your keyring and just try using it without any other keys or bits of metal near it and see if that improves things.

It is not related to the battery that you might have inside the key for remote locking/unlocking.

[Paj 77]

I have changed the battery in the key. 
It’s intermittently happening. So at the moment the fault isn’t showing and the car starts no problem. But obviously it could come back anytime. I’ll try removing the key next time? 
would you say it’s the key. They can be tested by an auto locksmith 

thanks for your reply 

[unofix]

As said in my original post it is caused by the car ignition immobiliser not been able to read the 'passive' transponder chip in the key. It is not related to the battery in the key which is purely for the remote operation of the lock/unlock.

Do you have more than one key ?  If you do, then does this problem happen with both keys ?

14 minutes ago, Paj 77 said:

They can be tested by an auto locksmith 

Not really. If the key was not being read all of the time then they may be able to say the transponder chip was faulty.

If the fault is random, and there are not other keys etc. on your keyring which maybe blocking/masking the car key, then the next most common problem is with the aerial receiver coil that is around the ignition switch, assuming that your car is not keyless start (push button start).

[Paj 77]

Apologies. I misunderstood in your first message regarding the battery in the key. 
I only have one key and there are no other keys on the key ring. 
Is the aerial receiver coil easily replaced? Or costly? 
I’ve had a quote for a new key £120 

[unofix]

Unfortunately I've no idea on the cost or for that matter what exactly is involved with replacing the aerial receiver coil on your model. On most Fords with the coil receiver is fitted around the ignition switch it takes about 30 minutes to replace.

A word of caution !!

Don't assume the aerial receiver coil is the cause of your problem. The immobiliser system is complex and the failure to read the transponder chip can be caused by many things.

Since you only have one key, it would be a wise move to get a second key regardless. You could loose or break your only key at anytime which would cause you major problems. Get a new key and see if that improves the situation before getting further in to the problem.

[Paj 77]

Ok. Thanks for your help

[Paj 77]

Would an obd2 reader help? 

[unofix]

Use the software FORScan on a laptop (It's free) and a good ELM327(modified) connecting cable.

FORScan: https://forscan.org/download.html

ELM327(modified): https://tunnelrat-electronics.fwscart.com/USB_Modified_with_switch_ELM327/p4541936_17045457.aspx

[Paj 77]

👍🏻 Thanks 

[Paj 77]

Sorry.. will that only read with the engine running? 
If I have the engine running the car lock symbol / fault won’t be on so how it pick this error up? 

[Tdci-Peter]

4 hours ago, Paj 77 said:

will that only read with the engine running? 

Forscan will work with the ignition on, regardless if the engine is running. If it does not work (fails to connect to the car), then this would indicate wiring or connector fault in the CAN bus. This fault is one possible cause of the immobiliser active problem you seem to have at times.

[Paj 77]

Ok thanks for your help 

 

[Paj 77]

Hi

just an update. Got an auto locksmith around. Tested the key and said it was defective. New key required at a cost of £70. 
All good so far which is great 

thanks for the advice all