See more from Ask Carzone 
When to change a Citroen C5's belt?
When should the timing chain or belt on a Citroen C5 be changed
Our answer:
Hi Jim,
As you've not given us any model year or engine details we're going to go with 2009-2012 1.6 diesel. Even that varies depending on when the engine was made. Pre-July 2012 the interval is 240,000km or 10 years, after that it's 180,000km or 10 years.
Have a motoring question? Ask us here!
Ask us anything motoring related and please provide as much information as possible so we can give you the most accurate advice.