Citroen C5 anti pollution fault

[Forevertonian]

I've got a C5 Mk1.
I've just had the EOLYS fluid topped up.
When I floor it anti pollution fault comes up.
It was doing it before I filled up the pat fluid up.
The fault stays on (usually) for about a day and a half then goes off.
The car does not miss a beat or smoke or anything whilst it's on.
I read elsewhere that this could be a low voltage fault and that the ECU has picked a fault that could be caused by the battery being old.
Could that be right?

[Paul-R]

Did you use a Diagbox or high end code reader to reset the level in the ECU?

[RichardW]

When was the fuel filter last changed?

[Forevertonian]

I haven't had the diagnostic reset yet.
I've no idea when the fuel filter was done.
I've had it about a year now and I haven't done it.
I hoofed it going out in the morning and it didn't do it then.
But it did it on the way back.
I did close to 300 miles in it yesterday and it didn't miss a beat.
The engine management light went out about 3 hours later.

[wheeler]

This could be loads of possible things causing this, you need a diagnostic done before anything else. The 2.2HDi is well known to clog up fuel filters well before they are due to be replaced but normally you get a loss of power or even cutting out on heavy load when this happens. The fact it does it under heavy load means it could be starting to get clogged.
Diagnostic first then report back. If there are any faults relating to fuel pressure you need to change the fuel filter before you do anything else.

Did you use the correct type of additive fluid? there are 2 different types for the mk1 depending on the RP number.

[Paul-R]

You should reset (or get someone to reset) the ECU so it "knows" how much fluid is present. If the level was showing as zero before you filled it up then it will still behave as though the fluid needs filling up.

Once that is done then see how it behaves.

EDIT
Hopefully you have an ECU that can be updated. There are stories of early Eolys ECUs that needed to be replaced when the fluid was refilled.

[Forevertonian]

Thanks guys, I think the pat fluid is correct because I got an independent citroen garage to do the job.
Mine's a 2.0 HDI.
But I think I'll get it reset and diagnosed.

[Paul-R]

If an indie did the filling could they have done the resetting as part of the job?