Conditions For Setting DTC

WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

The PCM detects a temperature difference between the ECT sensor and the IAT sensor of more than 180°F (100° C) at start up.
The time spent cranking the engine without starting is more than 5 seconds, with a temperature difference between the ECT and the IAT sensor more than 27°F (15°C).
The PCM detects a temperature difference between the ECT sensor and the IAT sensor of more than 27°F (15°C), then the vehicle must be driven for 5 minutes over 15 mph (24 km/h). If the IAT sensor temperature decreases more than 12.6°F (7°C) then a block heater is detected and the test is aborted. If the IAT sensor temperature does not decrease, then a block heater was not detected and DTC P0116 sets.