Fault codes wont clear????

[gumby6371]

Plugged planet in yesterday and ran a global test;
Couple of glow plug related faults - ignored
Sat Nav - ignore
MFD fault - looks fine to me - ignore
Turbo pressure too high - As this has now been sorted I went about clearing the fault
I confirmed fault being read and it took me to another screen to enter mileage etc, hit ok and it thought for a second or two then gave me a communication error message and refused to clear the fault.
It was perfectly happy to clear other faults but not on the engine ECU??

I had the engine running all the time so now I'm wondering if it needs to be turned off to clear the fault?? Must admit I didn't think of that yesterday.

Any other possibilities???

I also got a new fault relating to air flow measured too low - open circuit - yadda yadda - which I assume is MAF related
I've got one of our suppliers sourcing a VDO one for me which hopefully will only cost 1 testicle instead of the pair!!!
On the plus side after a few repairs and a bit of tinkering I am managing to get 37-38MPG around town but that does involve driving like Miss Daisy, maybe a new MAF sensor will give me the same economy with my usual 'is that the time I was supposed to be there now!' driving style, we shall see.

[Doggy]

Any time I've cleared engine ecu faults, it has always asked me to turn the ignition off for a few seconds, then back on. Always done it with the engine stopped.

BTW, when you get to the enter mileage screen, you can just press F1 & ignore it - no point storing it unless you're aiming to upload it to PSA's server.

[mjb]

I've had pp2000/lexia refuse to clear engine ecu faults when there's still a permanent fault condition present

[GingerMagic]

I must admit sometimes my faults don't clear, but normally they will on the next plug in session....

I assume it must be me just pressing the wrong button, or forgetting to configure, or my cars French, meh...

[gumby6371]

Thanks for the responses gents I'll give it a go with engine off/ignition on.