An apparatus for controlling fuel pressure in an engine having a cylinder, the device comprising: fuel injection means for injecting fuel into the cylinder; ignition means for igniting a mixture of the injected fuel and air; a catalyst for removing pollutants from exhaust emitted by the engine; and control means for controlling the fuel injection means and the ignition means, the control means being arranged to select a combustion mode of the engine from at least a homogeneous combustion mode in which the fuel injection means injects the fuel during the intake stroke of the cylinder and the ignition means ignites the fuel before compression top dead center and a combustion mode for raising the temperature of the catalyst; wherein the control means is arranged to control the fuel injection means to inject the fuel based on a target fuel pressure according to the selected combustion mode, and to detect whether or not a request is present for raising the temperature of the catalyst; wherein in the homogenous combustion mode, when the control means detects that a request is present for raising the temperature of the catalyst, the control means sets the target fuel pressure to be a first target fuel pressure, and when the control means detects that a request is not present for raising the temperature of the catalyst, the control means sets the target fuel pressure to be a second target fuel pressure, the second target fuel pressure being lower than the first target fuel pressure; and wherein the first target pressure corresponds to a target pressure required for operating the engine in the combustion mode for raising the temperature of the catalyst. fuel injection means for injecting fuel into the cylinder; ignition means for igniting a mixture of the injected fuel and air; a catalyst for removing pollutants from exhaust emitted by the engine; and control means for controlling the fuel injection means and the ignition means, the control means being arranged to select a combustion mode of the engine from at least a homogeneous combustion mode in which the fuel injection means injects the fuel during the intake stroke of the cylinder and the ignition means ignites the fuel before compression top dead center and a combustion mode for raising the temperature of the catalyst; wherein the control means is arranged to control the fuel injection means to inject the fuel based on a target fuel pressure according to the selected combustion mode, and to detect whether or not a request is present for raising the temperature of the catalyst; wherein in the homogenous combustion mode, when the control means detects that a request is present for raising the temperature of the catalyst, the control means sets the target fuel pressure to be a first target fuel pressure, and when the control means detects that a request is not present for raising the temperature of the catalyst, the control means sets the target fuel pressure to be a second target fuel pressure, the second target fuel pressure being lower than the first target fuel pressure; and wherein the first target pressure corresponds to a target pressure required for operating the engine in the combustion mode for raising the temperature of the catalyst.