A system has been researched over the past 3 years for reducing the exhaust pollutants from diesel engines for light commercial vehicles. The system researched achieves Euro 6 standards for reduction of polluting gases (CO, HC, PM, NO). It consists of 4 main sections: 1. A heater and heat exchanger (HE); 2. A CO/HC oxidising catalyst (DOC); 3. Pt catalyst on a diesel particulate filter (DPF); 4. A NO reducing reaction (SCR) within the DPF. The system operates as follows. The exhaust gas contains oxidising gases, namely both $O_2$ and $NO_2$. The levels of CO and HC are oxidised by $O_2$ to $CO_2$ for temperatures above $200^{circ}C$. Carbon (PM) is oxidised to $CO_2$ by $NO_2$ but requires a temperature above $250^{circ}C$. The operating exhaust temperature of $300^{circ}C$ is ideal for the removal of NO by using the Pt catalyst and the CO generated within the DPF. The heater is required to be able to raise the exhaust temperature at any time to $300^{circ}C$ in order to optimise the performance of the system, since diesel engine exhaust temperatures vary between $160^{circ}C$ (slow speeds) to $350^{circ}C$ (high speeds). Considerable heat is required (~3 kW) to maintain the exhaust gas for a 2l engine at $300^{circ}C$ for engine idle conditions. Therefore a heat exchanger is required to re-circulate the input heat and thereby reduce the maximum power consumption to a maximum of 500W over the engine full operating test cycle. This energy is supplied by the engine battery and alternator. Experimental results have been obtained for the exhaust from a Kubota diesel engine and the reductions in exhaust emissions of 83% (CO/HC), 58% (NOx) and 99% (PM) were obtained. The PM was continuously cleaned so that there was no build up of back pressure.