Conditions For Setting DTC

WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. 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 (15°C) between the ECT and the IAT, the vehicle must be driven for 7 minutes over 15 MPH. If the IAT decreases more than 5.4°F (3°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; or, the temperature difference between the ECT and the IAT at start up is more than 252°F (140°C).
The time spent cranking the engine, without starting is more than 10 seconds.