LONDON, England - The fuel supplied by French oil giant Total could be causing Red Bull's repeated 2014 problems with the mandatory fuel-flow sensor.It emerges that, during qualifying in Shanghai, the reigning World champion team had more trouble with the Gill-supplied device.To avoid a Melbourne-style disqualification, Red Bull reportedly adhered to an interim agreement reached with the governing International Automobile Federation to revert to other measurements in the event of a sensor failure.Meanwhile, the search to cure the problem continues.SUSPECT SEALSpeed Week correspondent Matthias Brunner has quoted federation technical expert Fabrice Lom as explaining that the Total-supplied fuel was probably the culprit. "The sensor has a seal that the chemical composition of the Total fuel could be damaging. If this is happening, then the sensor would not work correctly."Less clear, however, is why the Total fuel is damaging mainly Red Bull's sensors and not those used by the other three Renault-powered teams.Meanwhile, it seems Red Bull is not ready to forgive rival team Mercedes after the German team called on the reigning World champions to be banned for three races for appealing against Daniel Ricciardo's Melbourne disqualification.Mercedes chairman Niki Lauda on Saturday made a peace offering in the form of a Sachertorte, a famous recipe of Vienna chocolate cake, but Red Bull's Dr Helmut Marko told Bild:"He thinks everything is over with a cake. I think the next time he wants to eat with us, he should put on a bulletproof vest."Stay with Wheels24 for the 2014 F1 season – fresh reports every day.