Conditions For Setting DTC

WARNING: This page is about a different car, the 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, 2002 Chevrolet Monte Carlo, and 2002 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

If the PCM detects a temperature difference of more than 27°F (915°C) between the ECT and the IAT, the vehicle must be driven for 5 minutes over 15 MPH. If the IAT decreases more than 12.6°F (7°C) then a block heater is indicated and the test is aborted. If the IAT temperature does not decrease, a block heater was not detected and this DTC will set.
The temperature difference between ECT and IAT at start-up is greater than 252°F (140°C).
The time spent cranking the engine, without starting is greater than 10 seconds.