one or more cylinders but at a different point in a stroke of the engine such that the additionally injected fuel is intended not to combust in the engine cylinders but to pass through to the exhaust fluid treatment apparatus 1 for oxidation in the doc 110 for example the injection of the fuel to be injected into the cylinder may occur when an exhaust valve of the cylinder is open the first mode fuel data value 270 may be different from the second mode fuel data value 275 since the appropriate amount of fuel to be injected may be different depending on the operating conditions of the engine the values may be considerably different when the doc is warming up compared with when the doc is running having already warmed up in the fig4 example the first mode fuel data values may be used when the doc is warming up and the second mode fuel data values may be used when the doc has already warmed up and is in a normal running mode an exhaust gas temperature may be lower during doc warm up than during normal running mode consequently during warm up there may be an increased risk that fuel intended for combustion in the doc may not combust in the doc due to the temperature being too low consequently unburnt fuel may pass out of the exhaust fluid treatment apparatus altogether which may be inefficient and undesirable for regulatory reasons therefore the amount.