engine management light

[Big Eb]

Morning all, i have a citroen xantia 2.0 hdi 110 estate year 2000,enginie managemaent light comes on now and again and causes no power loss then sometimes it will come on with power loss,switch it off and on again then it's fine, anybody got any ideas,been on a diagnostic and had the fault cleared and problem solved front hose clip loose , but still has this intermittent fault.
thanks

[thorter]

This is a symptom of a marginal fault where the ECU carries out a crosscheck that sometimes is out of spec and sometimes OK. I had a similar fault on an identical car about 15 years ago, and it was due to an air leak in the vacuum feed to the turbo waste gate. It was in fact merely due to the rubber pipe at the waste gate being loose, which allowed enough leakage that the applied amount of vacuum sometimes did not result in the required boost. See https://www.frenchcarforum.co.uk/forum/ ... 80#p295780 It might be somewhere to start. Also check for partial blockage of vacuum pump connector which has quite a small bore.

[Big Eb]

Ok,thanks, will have a look-see