Conditions for Running the DTC

WARNING: This page is about a different car, the 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

P0502

DTCs P0117, P0118, P0119, P0128, P0335, P0336, P0338 or P0501 are not set.
The decel fuel cut-off (DFCO) is active.
The engine coolant temperature is more than 40°C (104°F).
The engine speed is 1,440-3,520 RPM.

P0503

DTC P0502 is not set.
The engine speed is 450-6,800 RPM for 8 seconds.
The system voltage is 10-18V.
The time since the last gear change is 6 seconds or more.
The engine speed change is more than 500 RPM in 2 seconds.