The ECM detects the following conditions:

•The intake manifold air temperature is greater than 90 °C (194.0 °F) for more than four seconds.
•The engine has been running for at least 30 seconds.
•The engine coolant temperature is above 99 °C (210.0 °F).

Probable Causes

1) Coolant level low
2) Debris/low air flow through charge air cooler
3) Heavy load on engine + high ambient air temperature