[AlCan]

Thanks, good point, it's a European car... EURO5 and all that. Maybe they needed to cost cut a bit after all that expense.

I charted Brake Pressure and tested on hard braking, but it seems to be the opposite. It jumps down when you'd least expect it, usually at the end of a mild braked deceleration, at about 25-20km/h. Gently pumping the brake pedal - i.e. On/Off-On/Off braking seems to trigger it most often, so I figured maybe it was running out of vacuum. But if there's nothing to detect it... ?

Have to admit, got excited when the low vacuum idea occurred to me, but I'm starting to run out of ideas

I'll have a dig through the manuals.