Conditions For Setting DTC
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
If the PCM detects a temperature difference between the ECT sensor and the IAT sensor of more than 27°F (15°C), the vehicle must be driven for more than 400 seconds over 15 MPH. If the IAT sensor temperature decreases more than 5°F (3°C), a block heater is detected and the test is aborted. If the IAT sensor temperature does not decrease, a block heater was not detected and DTC P0116 sets.