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