Citroen only uses the caudalimetro to know the percentage of EGR that the vehicle is doing, due to issues of anticontamination of the law, so it is because you do not notice difference in the engine when you disagree it. What happens is that the witness is turned on when it starts it unplugged and the defect of the signal flower short circuit to + and a air theme signal short circuit to the +. When the flow failure does not turn on the witness, if not after several operating cycles in which it detects the error. It depends on the failure, the witness can only turn on or also enter in degraded mode, that is, it does not pass about 2000rpm. The first thing you have to do is start from 0. Leave the calculator without failures, put the via 3 to a direct mass as they told you in the previous message, because it is true that it is a reform of Citroen, it proves that it arrives empty to the EGR (a idle has to reach about 0.4Bar) and that the exhaust gas tube that reaches the EGR is not clogged (it happens very often, the defect would be very often signal value too high). If everything is correct, the failure can continue to be the flow.