Faulty Door Key?

[yorkie59]

Hi why would my car key suddenly lose its code and unable the car to start? Faulty key or faulty immobiliser.

[Johndouglas]

How old is the battery in the plip

[paul.h]

Does the car start with the spare key, if not,

 

- does the car turn over on the starter motor ?

- are there any messages or the engine management light lit to indicate what may be wrong ?

- it may be an immobilser fault or another fault that prevents the engine starting. Ideally a check under the bonnet for anything obviously wrong but then a diagnostic check by a Citroen dealer or Citroen specialist may be needed.