{HEAD ~ Particulates} in the trap are ignited and burnt off by {TAIL ~ exhaust gas} whose temperature has been raised by the electric heater 
are burnt off by
{ HEAD ~ Particulates } in the trap are ignited and burnt off by { TAIL ~ exhaust gas } whose temperature has been raised by the electric heater
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH