Are you sure this has variable vanes? I've not seen it on a 110bhp 2.0. I've had issues with vehicles going into LOS when towing due to the fuel flow regulator hitting its end stop. This issue is worse if they've been 'powerboxed' or similar.

As to clearing fault codes, have you tried letting the ecu shut down and then clearing codes before you start the engine? Some Citroens can be strange in that way.

HTH
Dick