Conditions for Setting the DTC

P0128

• The ECM detects that the actual engine coolant temperature is 11°C (20°F) colder than the calculated thermostat regulating temperature of 89°C (192°F), for greater than 4 seconds or for a cumulative of 30 seconds.

  OR

• The ECM detects that the actual engine coolant temperature is 10°C (18°F) colder than the calculated ECT for greater than 1 second or a cumulative of 10 seconds.