Kubota M4N-071 Operator's Manual page 50

OPERATING THE ENGINE
3. The 40 hours warning record will be reset if any fault has not been detected over 40 hours from the
repair.
If a fault is detected after the 40 hours warning record reset, then the new countdown will be stated.
44
SELECTIVE CATALYTIC REDUCTION (SCR) MUFFLER
M4N-071, M5N-091, M5N-111