PUCHASE FROM PRIVATE PARTY IN FEBRUARY, NISSAN RAN DIAGNOSTICS IMMEDIATELY AFTER PURCHASE. LEAK WAS NOT RECORDED. ACCIDENT HAPPENED IN JUNE, VEHICLE RETURNED IN SEPTEMBER, APPROXIMATELY A WEEK AFTER PICK UP, CODED LEAK IN EMULATION SYSTEM, MANIFOLD/EXHAUST CAUSING FUMES TO BACK UP INTO TRUCK WHILE STOPPED, EXTREME FUEL CONSUMPTION AND LACK OF POWER, CAUSING IDLE TO IDLE LOW AT STOP. THIS DEVELOPED AFTER A SIDESWIPED HIT ACCIDENT AND TRANSMISSION BEING REPLACED. LEFT AND RIGHT SENSOR ALSO CODED.